The document discusses bloodstain pattern analysis (BPA), which analyzes bloodstains at crime scenes to reconstruct events. BPA has been used since the late 19th century. Stains are classified by velocity (low, medium, high) and morphology (passive, transfer, projected). Analysts examine stain patterns to determine the area of convergence and origin to deduce the positions of victim and assailant. BPA supports other forensic evidence and can refute witness statements, but does not determine all crime details on its own.

1. BLOODSTAIN PATTERN ANALYSIS

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

3. 1. INTRODUCTION
AND HISTORY
A projected blood
stain found in a
crime scene (below)
Bloodstain pattern analysis or
BPA is the interpretation of
bloodstains at crime scenes in
order to recreate actions that
caused the bloodshed.
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 interpreted from it.
A blood stain is a mark or
discolouration on a fabric, fiber
or on a surface caused by blood.

4.  Blood behaves according to certain scientific principles. Hence, trained analysts can
examine the blood left behind and draw conclusions as to how the bloodshed
occurred. An analyst can categorize the bloodstains which can assist the analysts to
recreate events before and after the bloodshed.
 Analysts can recognize the shape, size, distribution and location of bloodstains to form
opinions about what happened and what had not happened. BPA uses the principles of
biology, physics and mathematics in answering questions such as :
 What caused the bloodshed?
 Where the blood came from?
 How were the wounds inflicted?
 From what direction the blood was smeared or projected?
 What were the positions of the victim and the assailant?
 What movements were made after the bloodshed?
 Does it support or refute witness statements or suspects confessions?
 BPA not only provides information on what could have happened but also what could
have not happened.

5. HISTORY OF
BPA
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 as well as showing that
the assailant struck the victim with his left
hand. (Image of Paul Kirk ).
Dr. Herbert MacDonell published concerning
the Flight Characteristics Of Blood and Stain
Patterns in 1971. He founded the IABPA in
1983 where BPA continues to grow and
develop.

6. 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. It forms a dark gel like
substance which becomes darker as time
progresses. The presence of blood clots can indicate
that the attack was prolonged. Also when
blood(circular) begins to clot its periphery begins to
turn dull first forming a crust which can be scraped
off. The periphery of the blood shows little
distortion if it falls on a hard smooth surface.
Distortion is more when it falls on a rough surface
like wood fiber etc

7. 2.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 and its shape.
 Based on velocity bloodstains are classified into:
 Low velocity stains
 Medium velocity stains
 High velocity stains

8. 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.

9. 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.

10. 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.

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

12. 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
(image) smear of a bloody hand and
bloody shoe print.

13. Image of an arterial
spurt in a crime scene.
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
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.

14. 3. BPA-
HOW IT IS DONE?
BPA starts with first documentation of the
bloodstains. This is done with notetaking,
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.

15. 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 ve
have been projected from a swinging or
flinged object.

16. 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.

17. 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. 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. 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. However, the tail part
of some stains if present is not considered as
either the width or length in the measurement
since it is a totally different factor.

18. Directionality is also another
variable to aid in area of
convergence determination.
If the stain is circular it means
the stain impacted at an angle
of 90 degrees. If the stain
impacted at an angle less than
90 degrees the resulting
bloodstain will have an
elongated appearance. In
addition the tail of the droplet
will indicate the direction at
which the stain impacted that
is, the opposite direction from
where the droplet originated
from.

19. 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.

20. 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.

21. 4.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.
In the given image, test to see the void
pattern formation is consistent with the one
found in the crime scene.

22. REFERENCES
 WWW.SWGSTAIN.ORG.IN
 WWW.FORENSICSCIENCESIMPLIFIED.ORG
 WWW.CRIMESCENEINVESTIGATOR.NET