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Pascal Goetgheluck/Science Photo Library
Forensic –
 science from                                                                                              The forensic team
                                                                                                           must collect as much
                                                                                                           evidence as is




fingerprints
                                                                                                           possible from the
                                                                                                           crime scene.




     to DNA
In the bedroom of 10 Main Street, Murrundrongo,
a man in his fifties lies dead on the floor next to
a bed . . .          . . . with a broken glass bottle
                   nearby; reddish-brown stains on the
                                                       The man may have died of natural
                                                       causes, the stains could be from spilt
                                walls, a red stain on the carpet and      red wine, and a cricket ball may have
                                the bathroom window smashed.              smashed the bathroom window weeks
Roger Beckmann                  What’s been going on – accident or        ago — or even after the death.
                                foul play?                                   To put the pieces together, a team
                                  This is the sort of puzzle that could   effort is required. Police officers will
                                confront a crime scene investigator       interview neighbours and gather
                                (CSI) from the police force. Crime        information about the dead person.
                                scene investigators, often referred       A doctor, or forensic pathologist, may
                                to as ‘scientific police’, are one part   be called to examine the body. The
                                of the forensic team whose skills are     police forensic team must look for
                                essential in modern police                clues as to what occurred, and try to
                                investigation. In the fictitious scene    reconstruct a possible sequence of
                                just described, police must determine     events.
                                whether or not a crime has occurred.
The science of crime                        material using the observations,
                                                                        measurements, physical evidence
                            Every day, many crimes are committed        and photos collected by the CSIs.
                            in Australia. To solve these crimes           They conduct:
                            effectively – so that criminals are         • chemical analysis of paint, glass,
                            brought to justice – the police need to       fibres, accelerants (substances
                            work very efficiently, using as many          used to start a fire), explosives
                            techniques as possible. Science has           (from discharged guns), inks and
                            become an essential tool for the              printer toners;
                            modern police force.                        • biological analysis, which includes
                               Originally, the word ‘forensic’ meant      analysis of DNA, body fluids,
                            anything relating to a law court. But         fingerprints and swabs;
                            today it refers to a whole new subject.     • document examination, which
                            Forensics or forensic science means           involves examining hand-writing,
                            using science to solve crime. But what        handwriting impressions (eg. from
                            exactly does a forensic scientist do?         a note written on top of a pad
                               The work of a forensic scientist falls     of paper), machine-generated
                            into three broad groups: field,               documents, and paper and ink
                            laboratory and medical.                       types; and
                               Field workers or CSIs attend the         • ballistics, which is the study of
                            scene of a suspected crime, record in         firearms and ammunition, and the
                            detail what is present, and collect as        identification of particular firearms
                            much evidence as possible – without           from fired cartridge cases and
                            contaminating the scene in the                bullets. Ballistics also involves
                            process. They search for marks left by        calculating the direction and




                                                                                                                                                               AFP Forensic Services.
                            implements such as crowbars, knives           distance that a bullet travelled.
                            or screwdrivers, or impressions from          Another type of lab work in some
                            shoes and vehicle tyres. CSIs also          police forces is toxicology. This means
                            investigate fires, explosions and illegal   detecting and identifying drugs and
                            drug laboratories.                          poisons, and determining their effects
                               The lab-based forensic scientists        on the body.
                            begin their painstaking analysis of



                            Science has become an
                            essential tool for the modern
                            police force.                                                                         Analysis of objects determine if they
                                                                                                                  were used in a crime.




                                                                                                                       The third area of forensic science –
                                                                                                                    medical – is usually beyond the scope
                                                                                                                    of police teams. Specialists are
AFP Forensic Services.




                                                                                                                    brought in as required. Forensic
                                                                                                                    pathologists are most frequently used,
                         Searching for evidence that
                         may help solve the crime.
                                                                                                                    but there are also forensic dentists
                                                                                                                    (to identify teeth and bite marks) and
                                                                                                                    forensic psychiatrists. The medical
                                                                                                                    experts use their skills to gain
                                                                                                                    evidence about causes of injury and
                                                                                                                    death, or about the identity, behaviour
                                                                                                                    and motivation of a criminal.
                                                                                                                       Occasionally, other specialists may
                                                                                                                    be used. Botanists may be called
                                                                                                                    upon to identify pollen types found
                                                                                                                    on clothing, while engineers may give
                                                                                                                    advice on machinery, building
                                                                                                                    collapses or major fires. A recent
                                                                                                                    development in forensic science is
                                                                                                                    information technology, which means
                                                                                                                    using knowledge of computers and
                                                                                                                    software. As such, police will often
                                                                                                                    look for information on a suspect or
                                                                                                                    victim’s computer. New forms of crime
                                                                                                                    – so-called cybercrime – are making
                                                                                                                    use of computers as criminal tools, for
                                                                                                                    example to acquire information illegally
                                                                                                                    by ‘hacking’.
Four main uses of forensics                  determine which areas to concentrate                                Is it like the TV
                                             their investigation on. For example,
In Australia, the police characterise four   they may use luminol, which detects                                 shows?
main uses of forensic investigation.         traces of blood by reacting with the                                Forensic scientists are quick to point
These are:                                   iron in the haemoglobin molecules                                   out that TV dramas about their work
1. To prove an element of an offence, for    that are within red blood cells. Luminol                            are inaccurate.
   example, to identify a substance as       glows when it comes into contact with                                  The most common misconception
   an illegal drug.                          blood. Sometimes it reveals small                                   is that most forensic work is involved
2. To associate or disassociate a            traces of blood that would normally                                 with murders. Instead, it is involved
   suspect from a crime scene or crime       be invisible.                                                       with house burglaries, drug offences,
   exhibit (for example, a weapon).             The presence of blood, however,                                  fires and vehicle accidents. Secondly,
                                             does not mean it is from a human, or                                it is not the forensic experts’ job to
3. To help determine a possible, or          even that it had anything to do with a
   probable, sequence of events.                                                                                 confirm what police investigators would
                                             crime. After all, people do occasionally                            like to hear. Forensic science, like any
4. To provide criminal intelligence, which   cut themselves, which could leave                                   form of science, involves having an
   means to give extra information to the    a tiny drop of blood on the carpet.                                 open mind and being impartial.
   police that may be used in the future.       In the case of the smashed window                                   The crime scene investigator or the
   For example, if illegal drugs are         at Number 10, the investigators                                     lab scientist cannot afford to hang on
   seized, careful analysis shows a          discovered traces of blood on the                                   to pet theories or preferred suspects.
   chemical ‘signature’ which may reveal     shards of glass, but the stains on                                  He or she must work to uncover facts
   what country or illegal laboratory        the bedroom wall, and the liquid on                                 that can be used as evidence. Quite
   produced them. This may help with         the carpet, were not from blood.                                    often, these facts may serve to rule
   other investigations.                                                                                         out many of the suspects that the
                                                                                                                 police have.
                                                                                                                    Finally, TV dramas tend to roll all
      Meanwhile, back at 10 Main Street,                                                                         forensic work into one person’s
   the crime scene investigators will
   thoroughly examine the area where the
                                             Increasingly,                                                       responsibilities. In real life, forensic
                                                                                                                 scientists are specialists. No single
   body was found. They will take detailed
   notes and photographs, look for
                                             CSIs are using                                                      person possesses all the knowledge
                                                                                                                 and expertise of every field of
   fingerprints, palm prints and sole
   prints; marks of tools and weapons;       specialised                                                         forensics. Solving crimes is very much
                                                                                                                 teamwork, and modern teams are
   marks from shoes; fibres from clothing
   or material; fragments of paint and       techniques                                                          large.
   glass and body fluids.
      Increasingly, CSIs are using
   specialised techniques, on site, to
                                             on site.
                                                                                                                 The cast of CSI (Crime Scene Investigation)
                                                                                        AFP Forensic Services.

                                                                                                                 WIN Television




   Laboratory based forensic
   employ a number of
   accurate scientific
   techniques.
WIN Television




                                           Jorja Fox from
                                           CSI, fires a gun
                                           to compare
                                           marks on the
                                           bullet and shell.




                 Answers from the
                 dead
                   Pathology is the study of disease,
                 and cause of death. A forensic
                 pathologist specialises in examining
                 dead bodies to determine how and




                                                                                                                                                                Constantino Margiotta/Science Image Library.
                 when death occurred.
                   As well as examining the body, either
                 on site or through photos taken at the
                 scene, the forensic pathologist may
                 also use x-ray imaging and will usually
                 conduct an autopsy or post-mortem.
                 A post-mortem is a careful dissection
                 of the corpse, which comes from the
                 Latin language meaning after-death.
                 The pathologist will also take samples
                 of body tissues, like blood, liver or
                 hair, for further analysis.
                                                               The corpse may reveal what caused a person’s death.



                                                                  One of the first tasks with a body                 evidence, linking a suspect to the
                                                               on site is to establish the time of                   crime. The remnants of explosive
                                                               death. The pathologist starts with                    material from a gunshot may also be
                                                               temperature. The normal temperature
                                                                                            o
                                                                                                                     present on the skin, for example, near
                                                               inside a human body is 37 C.                          a bullet hole. Such residues, and
                                                               A pathologist will take the temperature               the bullet wound itself, can give
                                                               inside the body, as well as the                       information about the type of bullet
                                                               temperature in the place where the                    used, as well as the distance and
                                                               body was found. The rate at which                     direction from which it was fired.
                                                               body temperature falls after death                       At the autopsy, pathologists start
                                                               depends on the external temperature,                  with carefully looking at the body and
                                                               the clothing worn, the size of the body,              its clothing. They then examine the
                                                               and its percentage of fat.                            skin — looking for cuts, scratches,
                                                                  After 12 hours, most dead bodies                   stabs, wounds or injection needle
                                                               are the same temperature as their                     marks — and the nails.
                                                               surroundings, therefore other methods                    The body found at Number 10 had
                                                               are required for determining the time                 a long thin scratch on the shin of the
                                                               of death. There are many gradual                      right leg, and had been dead for about
                                                               changes that take place after death.                  eight hours before police arrived in the
                                                               These occur in a particular sequence,                 morning.
                                                               concluding with total decomposition.
                                                               Skilled pathologists can usually use
                                                               these changes to assess, roughly,
                                                                                                                     Secrets from within
                                                               when death occurred.                                    Although a body does not always
                                                                  After the dead body has been                       show marks on the outside, there is
                                                               examined at the scene, it is wrapped                  often evidence inside that will be
                                                               for transport. This is done very                      revealed during the autopsy. In our
                                                               carefully because small details — like                scenario, the pathologist found the
                                                               fragments of skin, hair or blood caught               back of the man’s skull cracked,
                                                               under a victim’s fingernails during a                 and a pool of blood inside the skull.
                                                               struggle — may provide crucial
An escape of blood from the blood
vessels like this is called a
haemorrhage. This type of internal
bleeding can be fatal, as the pressure
of the leaked blood damages the
brain.
   There are other clues within a body
that can show up during an autopsy.
For example, a large blood clot within
a major artery or vein, or even in the
heart itself, may be a cause of natural
death, which would rule out foul play.
   Samples of a person’s stomach
contents can reveal the last food
eaten. Blood analysis will show the
existence of any poisons, illegal drugs
or medicines. Urine in the bladder may        AFP Forensic Services.
also be analysed.
   Analysis of the blood from the body
found at 10 Main Street showed a high
concentration of alcohol. Stomach
analysis revealed the remains of red
wine and spirits. Also, damage to the
liver was a telltale sign that the                                                                                DNA fingerprinting has become a powerful tool in helping solve crime.
deceased had been a heavy drinker
of alcohol.                                                            New prints are taken by a laser-                 DNA analysis does not enable
                                                                       scanning procedure, where the hand             scientists to build up a picture of
Print precision                                                        is placed on a flat glass plate, and its       a person from their DNA. The only
                                                                       print is stored and compared to other          characteristic that the DNA tells us is
Analysis of fingerprints is probably the                               prints electronically.                         the sex of the person. DNA profiling is
most well known use of forensic                                           A new form of identification relies         only used to compare different DNA
science. Each fingertip has a pattern                                  on DNA, which carries the genetic              samples, and to determine whether or
of fine skin ridges that are slightly                                  information of each person. Everyone’s         not they could be from the same
different for every person — even                                      DNA is different (except for identical         person.
identical twins.                                                       twins). DNA profiling or typing is
                                                                       sometimes called DNA fingerprinting
                                                                       because it allows police to identify
                                                                                                                      Putting it all
                                                                       an individual in the same way as               together
                                                                       fingerprints do. DNA can be extracted          In our investigation of Number 10,
                                                                       from any body fluid (blood, saliva,            blood found on a shard of glass from
                                                                       sweat, nasal mucus etc) or from                the broken window yielded DNA
                                                                       fragments of a body (hair roots,               identical to the dead man. The scratch
                                                                       torn skin or flesh).                           on his shin was recent, and probably
                                                                          Forensic scientists do not look             the source of the blood on the glass.
                                                                       at the whole of a person’s DNA                    The sticky red liquid on the carpet
                                                                       sequence, but rather a sub-set — a             was found to be port wine, some of
                                                                       DNA profile. DNA profiles are a very           which was also found on the broken
                                                                       powerful means of determining                  bottle. The source of the wall stains
                                                                       whether two or more samples may or             could not be determined, but they were
 Everyone has a unique set of fingerprints.                            may not have come from the same                not caused by blood.
                                                                       person. If DNA profiles do not match,             Police interviewed neighbours
                                                                       they came from different people.               separately, and their statements
  A fingerprint is composed of grease                                  However, if they do match, there is            confirmed that the man, a heavy
and dried sweat left behind by the tips                                still a very slight chance that they           drinker, often arrived home late at
of the fingers. The palms of the hand                                  may have come from different people.           night and had difficulty finding (and
also leave identifiable prints, as do the                                 DNA is the same in every cell of the        using) his keys. Sometimes he even
soles of the feet.                                                     body, and stays the same throughout            tried to bang down his own door,
  Fingerprints can be detected on a                                    life. As such, DNA profiles taken at           or else fall asleep in the bushes.
vast range of different surfaces using                                 different times and places can be                 On the night he died, someone had
a variety of techniques. The police                                    compared in order to determine                 heard his drunken singing. It was
keep a huge national database of                                       whether or not they come from the              probable that he broke the window to
prints taken from charged criminals.                                   same person.                                   gain entry to his own house, as it was
                                                                                                                      too cold a night to stay outside. The
DNA analysis does not enable                                                                                          forensic evidence suggested that,
                                                                                                                      while drunk, he fell onto a metal
                                                                                                                      radiator near his bed and died from
scientists to build up a picture                                                                                      the blow to his head. The bottle that
                                                                                                                      he was holding, broke as a result of
of a person from their DNA.                                                                                           his fall.
AFP Forensic Services.
Counting crime
Across Australia, the following crimes
were recorded in 2000:
approximately 227,000 residential
burglaries;
    139,094 motor vehicle thefts;
    15,630 sexual assaults;
    9 474 armed robberies; and
    342 murders.
It is important to realise that these
figures show recorded crime. Many
minor crimes and some serious crimes
are not reported to, or discovered, by
the police.
To establish the extent of crime in a
community, figures are often expressed
as rates per 100,000 people. This
shows that in Australia last year there
were just under 2 murders per 100,000
people.
It’s interesting to compare Australia’s
murder rate with other countries:
  Brazil 10 per 100,000
  USA      7 per 100,000                                              Everywhere we go,
                                                                      we leave a telltale
  Switzerland       3 per 100,000                                     sign of our presence.
  Japan 1 per 100,000

These comparisons may be slightly            It is almost                                     The perfect crime?
inaccurate because of differences in the                                                      There are many examples of unsolved
way crime statistics are collected and
used around the world.
                                             impossible to                                    and undetected crimes, especially from
                                                                                              the past when forensic techniques
Even within a country, different areas       be in a place                                    were less sophisticated. Even today,
experience different crime rates.                                                             there are still crimes committed where
Therefore, figures can give a misleading     without                                          the criminal is not discovered.
picture of your likelihood of being a                                                            More often, however, forensic
victim of crime. What is clear, however,     leaving a                                        evidence allows police to link a
is that in Australia, violent crime is far                                                    suspect to a crime without enough
less common than theft.                      trace of your                                    certainty to convince a court, and so
                                                                                              the suspect is not found guilty. If there
                                             presence.                                        are no other suspects connected to
                                                                                              the crime, the police must look for
                                                                                              more evidence – for example, from
                                                                                              later witnesses.
Correlation is not proof                                                                         However, many criminals are
                                                                                              unaware of just how readily they can
As in all areas of science, evidence         at the scene, may belong to someone              be linked to a crime by the skilled use
from forensic investigation does not         else. There are a number of                      of modern forensic techniques. It is
mean proof. A correlation between two        possibilities. The suspect may have:             almost impossible to be in a place
things does not mean that one causes         • committed the murder;                          without leaving a trace of your
the other.                                   • been present at the crime,                     presence in the form of a hair,
   For example, you might observe that          without committing the offence;               discarded skin cells, clothing fibres
most people involved in car crashes          • been present at the scene                      or traces of saliva.
wear seat belts, but this doesn’t mean          innocently or suspiciously before
that seat belts cause crashes. Your             the crime occurred;
observation is correct, but you cannot       • arrived after the crime and left in
use it as evidence for the cause of             fright; or,
accidents. You need to make further          • been nowhere near the scene and
observations – for example, of people           his jacket was used by someone
in cars who are not involved in                 else with or without his knowledge.             The author would like to thank the
crashes.                                                                                      Australian Federal Police Forensic
   Pieces of evidence may not always           Therefore, all evidence must be                Services, in particular Mr Karl Kent, for
agree. A fibre found at a murder scene       taken together. Very rarely is one piece         generous assistance with this article.
may match a male suspect’s jacket,           of evidence conclusive proof.
but other evidence, such as DNA found

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Forensic science%20from%20fingerprints%20to%20 dna

  • 1. Pascal Goetgheluck/Science Photo Library Forensic – science from The forensic team must collect as much evidence as is fingerprints possible from the crime scene. to DNA In the bedroom of 10 Main Street, Murrundrongo, a man in his fifties lies dead on the floor next to a bed . . . . . . with a broken glass bottle nearby; reddish-brown stains on the The man may have died of natural causes, the stains could be from spilt walls, a red stain on the carpet and red wine, and a cricket ball may have the bathroom window smashed. smashed the bathroom window weeks Roger Beckmann What’s been going on – accident or ago — or even after the death. foul play? To put the pieces together, a team This is the sort of puzzle that could effort is required. Police officers will confront a crime scene investigator interview neighbours and gather (CSI) from the police force. Crime information about the dead person. scene investigators, often referred A doctor, or forensic pathologist, may to as ‘scientific police’, are one part be called to examine the body. The of the forensic team whose skills are police forensic team must look for essential in modern police clues as to what occurred, and try to investigation. In the fictitious scene reconstruct a possible sequence of just described, police must determine events. whether or not a crime has occurred.
  • 2. The science of crime material using the observations, measurements, physical evidence Every day, many crimes are committed and photos collected by the CSIs. in Australia. To solve these crimes They conduct: effectively – so that criminals are • chemical analysis of paint, glass, brought to justice – the police need to fibres, accelerants (substances work very efficiently, using as many used to start a fire), explosives techniques as possible. Science has (from discharged guns), inks and become an essential tool for the printer toners; modern police force. • biological analysis, which includes Originally, the word ‘forensic’ meant analysis of DNA, body fluids, anything relating to a law court. But fingerprints and swabs; today it refers to a whole new subject. • document examination, which Forensics or forensic science means involves examining hand-writing, using science to solve crime. But what handwriting impressions (eg. from exactly does a forensic scientist do? a note written on top of a pad The work of a forensic scientist falls of paper), machine-generated into three broad groups: field, documents, and paper and ink laboratory and medical. types; and Field workers or CSIs attend the • ballistics, which is the study of scene of a suspected crime, record in firearms and ammunition, and the detail what is present, and collect as identification of particular firearms much evidence as possible – without from fired cartridge cases and contaminating the scene in the bullets. Ballistics also involves process. They search for marks left by calculating the direction and AFP Forensic Services. implements such as crowbars, knives distance that a bullet travelled. or screwdrivers, or impressions from Another type of lab work in some shoes and vehicle tyres. CSIs also police forces is toxicology. This means investigate fires, explosions and illegal detecting and identifying drugs and drug laboratories. poisons, and determining their effects The lab-based forensic scientists on the body. begin their painstaking analysis of Science has become an essential tool for the modern police force. Analysis of objects determine if they were used in a crime. The third area of forensic science – medical – is usually beyond the scope of police teams. Specialists are AFP Forensic Services. brought in as required. Forensic pathologists are most frequently used, Searching for evidence that may help solve the crime. but there are also forensic dentists (to identify teeth and bite marks) and forensic psychiatrists. The medical experts use their skills to gain evidence about causes of injury and death, or about the identity, behaviour and motivation of a criminal. Occasionally, other specialists may be used. Botanists may be called upon to identify pollen types found on clothing, while engineers may give advice on machinery, building collapses or major fires. A recent development in forensic science is information technology, which means using knowledge of computers and software. As such, police will often look for information on a suspect or victim’s computer. New forms of crime – so-called cybercrime – are making use of computers as criminal tools, for example to acquire information illegally by ‘hacking’.
  • 3. Four main uses of forensics determine which areas to concentrate Is it like the TV their investigation on. For example, In Australia, the police characterise four they may use luminol, which detects shows? main uses of forensic investigation. traces of blood by reacting with the Forensic scientists are quick to point These are: iron in the haemoglobin molecules out that TV dramas about their work 1. To prove an element of an offence, for that are within red blood cells. Luminol are inaccurate. example, to identify a substance as glows when it comes into contact with The most common misconception an illegal drug. blood. Sometimes it reveals small is that most forensic work is involved 2. To associate or disassociate a traces of blood that would normally with murders. Instead, it is involved suspect from a crime scene or crime be invisible. with house burglaries, drug offences, exhibit (for example, a weapon). The presence of blood, however, fires and vehicle accidents. Secondly, does not mean it is from a human, or it is not the forensic experts’ job to 3. To help determine a possible, or even that it had anything to do with a probable, sequence of events. confirm what police investigators would crime. After all, people do occasionally like to hear. Forensic science, like any 4. To provide criminal intelligence, which cut themselves, which could leave form of science, involves having an means to give extra information to the a tiny drop of blood on the carpet. open mind and being impartial. police that may be used in the future. In the case of the smashed window The crime scene investigator or the For example, if illegal drugs are at Number 10, the investigators lab scientist cannot afford to hang on seized, careful analysis shows a discovered traces of blood on the to pet theories or preferred suspects. chemical ‘signature’ which may reveal shards of glass, but the stains on He or she must work to uncover facts what country or illegal laboratory the bedroom wall, and the liquid on that can be used as evidence. Quite produced them. This may help with the carpet, were not from blood. often, these facts may serve to rule other investigations. out many of the suspects that the police have. Finally, TV dramas tend to roll all Meanwhile, back at 10 Main Street, forensic work into one person’s the crime scene investigators will thoroughly examine the area where the Increasingly, responsibilities. In real life, forensic scientists are specialists. No single body was found. They will take detailed notes and photographs, look for CSIs are using person possesses all the knowledge and expertise of every field of fingerprints, palm prints and sole prints; marks of tools and weapons; specialised forensics. Solving crimes is very much teamwork, and modern teams are marks from shoes; fibres from clothing or material; fragments of paint and techniques large. glass and body fluids. Increasingly, CSIs are using specialised techniques, on site, to on site. The cast of CSI (Crime Scene Investigation) AFP Forensic Services. WIN Television Laboratory based forensic employ a number of accurate scientific techniques.
  • 4. WIN Television Jorja Fox from CSI, fires a gun to compare marks on the bullet and shell. Answers from the dead Pathology is the study of disease, and cause of death. A forensic pathologist specialises in examining dead bodies to determine how and Constantino Margiotta/Science Image Library. when death occurred. As well as examining the body, either on site or through photos taken at the scene, the forensic pathologist may also use x-ray imaging and will usually conduct an autopsy or post-mortem. A post-mortem is a careful dissection of the corpse, which comes from the Latin language meaning after-death. The pathologist will also take samples of body tissues, like blood, liver or hair, for further analysis. The corpse may reveal what caused a person’s death. One of the first tasks with a body evidence, linking a suspect to the on site is to establish the time of crime. The remnants of explosive death. The pathologist starts with material from a gunshot may also be temperature. The normal temperature o present on the skin, for example, near inside a human body is 37 C. a bullet hole. Such residues, and A pathologist will take the temperature the bullet wound itself, can give inside the body, as well as the information about the type of bullet temperature in the place where the used, as well as the distance and body was found. The rate at which direction from which it was fired. body temperature falls after death At the autopsy, pathologists start depends on the external temperature, with carefully looking at the body and the clothing worn, the size of the body, its clothing. They then examine the and its percentage of fat. skin — looking for cuts, scratches, After 12 hours, most dead bodies stabs, wounds or injection needle are the same temperature as their marks — and the nails. surroundings, therefore other methods The body found at Number 10 had are required for determining the time a long thin scratch on the shin of the of death. There are many gradual right leg, and had been dead for about changes that take place after death. eight hours before police arrived in the These occur in a particular sequence, morning. concluding with total decomposition. Skilled pathologists can usually use these changes to assess, roughly, Secrets from within when death occurred. Although a body does not always After the dead body has been show marks on the outside, there is examined at the scene, it is wrapped often evidence inside that will be for transport. This is done very revealed during the autopsy. In our carefully because small details — like scenario, the pathologist found the fragments of skin, hair or blood caught back of the man’s skull cracked, under a victim’s fingernails during a and a pool of blood inside the skull. struggle — may provide crucial
  • 5. An escape of blood from the blood vessels like this is called a haemorrhage. This type of internal bleeding can be fatal, as the pressure of the leaked blood damages the brain. There are other clues within a body that can show up during an autopsy. For example, a large blood clot within a major artery or vein, or even in the heart itself, may be a cause of natural death, which would rule out foul play. Samples of a person’s stomach contents can reveal the last food eaten. Blood analysis will show the existence of any poisons, illegal drugs or medicines. Urine in the bladder may AFP Forensic Services. also be analysed. Analysis of the blood from the body found at 10 Main Street showed a high concentration of alcohol. Stomach analysis revealed the remains of red wine and spirits. Also, damage to the liver was a telltale sign that the DNA fingerprinting has become a powerful tool in helping solve crime. deceased had been a heavy drinker of alcohol. New prints are taken by a laser- DNA analysis does not enable scanning procedure, where the hand scientists to build up a picture of Print precision is placed on a flat glass plate, and its a person from their DNA. The only print is stored and compared to other characteristic that the DNA tells us is Analysis of fingerprints is probably the prints electronically. the sex of the person. DNA profiling is most well known use of forensic A new form of identification relies only used to compare different DNA science. Each fingertip has a pattern on DNA, which carries the genetic samples, and to determine whether or of fine skin ridges that are slightly information of each person. Everyone’s not they could be from the same different for every person — even DNA is different (except for identical person. identical twins. twins). DNA profiling or typing is sometimes called DNA fingerprinting because it allows police to identify Putting it all an individual in the same way as together fingerprints do. DNA can be extracted In our investigation of Number 10, from any body fluid (blood, saliva, blood found on a shard of glass from sweat, nasal mucus etc) or from the broken window yielded DNA fragments of a body (hair roots, identical to the dead man. The scratch torn skin or flesh). on his shin was recent, and probably Forensic scientists do not look the source of the blood on the glass. at the whole of a person’s DNA The sticky red liquid on the carpet sequence, but rather a sub-set — a was found to be port wine, some of DNA profile. DNA profiles are a very which was also found on the broken powerful means of determining bottle. The source of the wall stains whether two or more samples may or could not be determined, but they were Everyone has a unique set of fingerprints. may not have come from the same not caused by blood. person. If DNA profiles do not match, Police interviewed neighbours they came from different people. separately, and their statements A fingerprint is composed of grease However, if they do match, there is confirmed that the man, a heavy and dried sweat left behind by the tips still a very slight chance that they drinker, often arrived home late at of the fingers. The palms of the hand may have come from different people. night and had difficulty finding (and also leave identifiable prints, as do the DNA is the same in every cell of the using) his keys. Sometimes he even soles of the feet. body, and stays the same throughout tried to bang down his own door, Fingerprints can be detected on a life. As such, DNA profiles taken at or else fall asleep in the bushes. vast range of different surfaces using different times and places can be On the night he died, someone had a variety of techniques. The police compared in order to determine heard his drunken singing. It was keep a huge national database of whether or not they come from the probable that he broke the window to prints taken from charged criminals. same person. gain entry to his own house, as it was too cold a night to stay outside. The DNA analysis does not enable forensic evidence suggested that, while drunk, he fell onto a metal radiator near his bed and died from scientists to build up a picture the blow to his head. The bottle that he was holding, broke as a result of of a person from their DNA. his fall.
  • 6. AFP Forensic Services. Counting crime Across Australia, the following crimes were recorded in 2000: approximately 227,000 residential burglaries; 139,094 motor vehicle thefts; 15,630 sexual assaults; 9 474 armed robberies; and 342 murders. It is important to realise that these figures show recorded crime. Many minor crimes and some serious crimes are not reported to, or discovered, by the police. To establish the extent of crime in a community, figures are often expressed as rates per 100,000 people. This shows that in Australia last year there were just under 2 murders per 100,000 people. It’s interesting to compare Australia’s murder rate with other countries: Brazil 10 per 100,000 USA 7 per 100,000 Everywhere we go, we leave a telltale Switzerland 3 per 100,000 sign of our presence. Japan 1 per 100,000 These comparisons may be slightly It is almost The perfect crime? inaccurate because of differences in the There are many examples of unsolved way crime statistics are collected and used around the world. impossible to and undetected crimes, especially from the past when forensic techniques Even within a country, different areas be in a place were less sophisticated. Even today, experience different crime rates. there are still crimes committed where Therefore, figures can give a misleading without the criminal is not discovered. picture of your likelihood of being a More often, however, forensic victim of crime. What is clear, however, leaving a evidence allows police to link a is that in Australia, violent crime is far suspect to a crime without enough less common than theft. trace of your certainty to convince a court, and so the suspect is not found guilty. If there presence. are no other suspects connected to the crime, the police must look for more evidence – for example, from later witnesses. Correlation is not proof However, many criminals are unaware of just how readily they can As in all areas of science, evidence at the scene, may belong to someone be linked to a crime by the skilled use from forensic investigation does not else. There are a number of of modern forensic techniques. It is mean proof. A correlation between two possibilities. The suspect may have: almost impossible to be in a place things does not mean that one causes • committed the murder; without leaving a trace of your the other. • been present at the crime, presence in the form of a hair, For example, you might observe that without committing the offence; discarded skin cells, clothing fibres most people involved in car crashes • been present at the scene or traces of saliva. wear seat belts, but this doesn’t mean innocently or suspiciously before that seat belts cause crashes. Your the crime occurred; observation is correct, but you cannot • arrived after the crime and left in use it as evidence for the cause of fright; or, accidents. You need to make further • been nowhere near the scene and observations – for example, of people his jacket was used by someone in cars who are not involved in else with or without his knowledge. The author would like to thank the crashes. Australian Federal Police Forensic Pieces of evidence may not always Therefore, all evidence must be Services, in particular Mr Karl Kent, for agree. A fibre found at a murder scene taken together. Very rarely is one piece generous assistance with this article. may match a male suspect’s jacket, of evidence conclusive proof. but other evidence, such as DNA found