This presentation is a brief about the analysis of blood patterns present at crime scene.

1. PRESENTATION
ON
BLOOD SPATTER PATTERN
ANALYSIS
DEPARTMENT OF FORENSIC SCIENCE [SAM HIGGINBOTTOM
UNIVERSITY OF AGRICULTURE, TECHNOLOGY & SCIENCES]
Formerly ALLAHABAD AGRICULTURAL INSTITUTE
PRYAGRAJ, INDIA
SUBMITTED TO- SUBMITTED BY-
Dr. Vaibhav Saran Sir PALLAVI KUMARI

3. CONTENT
1. INTRODUCTION AND BRIEF HISTORY
2.CLASSIFICATION OF BLOODSTAIN PATTERNS
3.BPA-HOW IT IS DONE?
4.CONCLUSION

4. INTRODUCTION
• Bloodstain pattern analysis or BPA is the interpretation
of bloodstains at crime scenes in order to recreate
actions that caused the bloodshed.
• Bloodstain pattern analysis (BPA) is an aspect of many
forensic investigations, particularly those involving
violence. It can help to determine the facts regarding an
incident, the events that occurred throughout and can be
supplemented by DNA analysis.
• BPA involves the examination of the number, pattern,
size, shape, and location of bloodstains.

5. • Blood stain created from the application of force to the area where
the blood originated.
The most important uses of bloodstain pattern analysis include:
• The reconstruction of the events of a crime or accident.
• To corroborate or refute statements of witness, victim or suspect.
• To bring about some certainty in cases where there is doubt as to
involvement in a crime.
• For the identification of areas with high likelihood of offender movement
for the prioritization of DNA samples.
•To differentiate between homicides, suicides and accidents.

6. Questioned to be answered…
•Did a crime occur is?
Homicide or suicide?
Homicide or accident?
• What kind of weapons was used?
• How many blows to the victim?
• How did victim react?
• What did the victim do after the suspect left the scene?

7. HISTORY OF BPA
 This field in Forensic Science became very much
recognized during the. late nineteenth century. Blood
being the most frequently encountered physical evidences
in variety of crime scenes has raised awareness as to what
could be interpret from it.
 Eduard Piotrowski is considered the earliest known
person to study on blood spatters (1895).
 In the case of State of Ohio vs. Samuel Sheppard, an
affidavit concerning evidence of blood spatters was
submitted to the court by
Paul Kirk. He showed the position of the victim and
assailant (culprit) as well as showing that the
assailant struck the victim with his left hand.

8. BLOOD
 In order to interpret bloodstains, we must know the basic principles
of blood. Blood has both liquid (plasma) and solid
parts(corpuscles).
 Blood is in liquid state inside the body as well as outside but only
for a short period of time. Blood when outside the body begins to
clot except from persons who suffer from hemophilia.
 The presence of blood clots can indicate that the attack was
prolonged.

9. • Blood is a fluid that makes up approximately 8% of the
weight of a human body.
• Females have approximately 4-5 litres while males have
between 5-6 litres.
• Blood is made up of cells (red blood cells and white
blood cells) plus platelets in a yellowish liquid called
plasma.
• Plasma contains gases (oxygen, carbon dioxide) and
molecules such as proteins, fats and carbohydrates
(sugars).

10. CLASSIFICATION OF
BLOODSTAIN PATTERNS
 Bloodstain classification is very significant to
investigators and analysts since it can yield information
about the position before and after death, the type of
force applied to cause the bloodstain, the direction from
where the blood spatter came from and the type of
weapon used on the victim. Also point of origin and
directionality can be interpreted which will be discussed
later.
 Classification is done based on-
○ Velocity of the blood.
○ Shape of blood.

11. Factors that affect bloodstain shape
 Force applied to the blood
 Surface characteristics
 Distance from surface
 Angle of impact
 Volume of blood
 Movement

12. Based on velocity bloodstains are
classified into
 Low velocity stains
 Medium velocity stains
 High velocity stains
Low velocity
High velocity

13. • Low velocity bloodstains is caused
by blood dripping. For example, nose
bleed or blood dripping from a
bludgeoned knife.
• The force of the blood hitting the
surface is 5 feet per second or less.
• The bloods diameter is large as 4 to
8 mm.

15. • Medium velocity bloodstain is caused by
beating with a blunt object like beating a
person with a baseball bat.
• The force of the blood spatter is between 5
and 100 feet per second.
• The diameter of the blood spatter is smaller
than that of low velocity blood spatter.
They even appear as a spray.

17. • High velocity spatter is caused by mainly
gunshots. It can also be caused by other
objects if enough force is exerted.
• The force of the blood spatter is more
than 100 feet per second.
• This causes the spatter to appear like a
fine spray. The droplet is less than 1 mm.

19. • Bloodstains are classified into:
1. Passive
2.Transfer
3.Projected
1. Passive bloodstains are due to the effect of the
gravitational force.
They are in the form of:
 Pools
 Drops
 Drips
 Clots

22. 2. Transfer stains are a result due to result of direct
contact between the target surface and the blood
source.
It can be in the form of:
 Smears or swipe
 Contact bleeding
 Smudge
 Wipes

24. • Cast off spatter(projected)- Gunshot spatter includes
back spatter and forward spatter associated with gunshot
wounds. These are mainly important in reconstruction of
shooting incidents. Back spatter are large and few droplets
whereas forward spatter are a fine mist.
• Blood spatter is a result due to the force other than
gravity, acting on the blood source.
It can be in the form of :
 Impact spatter(mainly gunshot spatter)
 Arterial spurt
 Expirated spurt

27. BPA (HOW IT IS DONE?)
 BPA starts with first documentation of the bloodstains. This is
done with note taking, sketches, photography and sometimes
videography is employed.
 Collection of articles that are transportable is done with
standard guidelines and precautions and BPA analysis
is conducted in the lab on such bloodstained items.
 Bloodstains found on walls and other immovable items
are documented and the BPA procedure is conducted at
the crime scene itself and then observations are
recorded and opinions are formed by the BPA analyst.

28. BPA analysis is divided into 2 phases:
 Physical examination
 Reconstruction
 Physical examination involves identifying
the stain pattern through its shape , size
and location and thus , determining cause
for the formation of the pattern.
 Here analysts need to be able to
categorize the bloodstain thus therefore aid
in determining the velocity at which the
stain traveled and the amount of force
acting on it giving an interpretation to what
mechanisms may have caused them.
 In the given image interpretation that it is a
cast off spatter shows that blood could
have been projected from a swinging or
flinged object.

29. • Reconstruction involves methods that are used to
answer certain questions such as:
Distance between blood source and
its impact?
The locations of the culprit and victim
relative to each other?
The type of crime that occurred?
Where is the person bleeding from?
Did the bleeding come from the
victim or the culprit?
Were there any other interventions?
Note: Always first document and collect to perform
presumptive tests on the stains before the BPA
analysis.

30. ANGLE OF IMPACT
 It is the angle at which the bloodstain
strikes the target surface. In order to
determine the angle of impact the width and
length of the stain must be known.
 In order to reconstruct such events analysts
have to determine the area of convergence
and the area of origin. In order to
determine the area of convergence(the
starting point of bloodshed) angle of impact
must be known.
 For example , if the width and length of
the stain are same then through the
given formula(from the image) we find
out that the angle is 90 degrees
indicating that the bloodstain fell
vertically.

32. AREA OF CONVERGENCE: Area of
convergence gives us the determination of
where the bloodshed originated from
whereas area of origin uses similar
techniques that were used in determining
area of convergence but gives us a three
dimensional interpretation thus telling us
about the positions of the victim and the
culprit during the time of the bloodshed
cause.
•A set of stains with distinct directionality
are chosen where straight lines are drawn
along their long axes and these straight lines
slowly intersect at a common point which is
the point or area of convergence.

33. AREA OF ORIGIN: After the determination
of the area of convergence strings are
attached to the stains selected for the area of
convergence calculation and then, by using a
protractor the strings are directed along the
angle of impacts of those stains to a support
system where the other end of each of the
strings used is attached to that system(like a
wall or a table).
• This complex time consuming procedure
indicates where the victim was located at the
time of the event.
• In the given image is the model of an area
of
origin in a crime scene indicating that the
victim was probably standing near the table
during the blood shedding event.

34. CONCLUSION
 BPA does not recreate incidents of the entire scenario
of the crime that has taken place. It mainly supports
findings of other forensic disciplines used in the
case.
 For example, BPA may show that the statement made
by the suspect about the victims suicide act is
false(on interpreting a void pattern).
 Instead, it showed that it was a homicide. However it
does not tell the age of the victim, whether the victim
was under the influence of a drug or whether he was
in a delusional state.