The document discusses blood spatter analysis and its use in crime scene reconstruction. It covers the following key points: 1. Blood spatter analysis examines the size, shape, and distribution of bloodstains to determine what happened, when it happened, and where it occurred. 2. Different factors like impact velocity and surface texture affect bloodstain patterns. Spherical blood drops that hit surfaces at an angle can indicate the distance and direction of impact. 3. A pattern is a group of spatters from the same force. Analyzing patterns can reveal the area of convergence where the blood source was located and the point of origin which provides information about the victim's posture. 4. Methods like

2. INDEX
 INTRODUCTION
 BIOLOGICAL AND PHYSICAL PROPERTIES OF
HUMAN BLOOD
 PATTERN
 AREA OF CONVERGENCE
 POINT OF ORIGIN
 IMPACT OF SPATTER AND MECHANISMS
 IMPORTANT AND LEGAL ASPECTS OF BPA

3. INTRODUCTION
 The goal of bloodstain pattern analysis is to determine
what, when and where of bloodshed events.
 WHAT is answered by examining the size of the
preponderance of the stains, the overall appearance of
the stains, and pattern distribution combined with the
case particulars.
 WHEN may be answered by alternations such as clotting
and sequencing.
 WHERE requires the analyst to determine the area of
convergence and area of origin that corresponds to the
location of the source of the blood.

4. Blood Spatter (or splatter)
Blood drops form different shapes and sizes
Blood spatter analysis uses the shapes and sizes to
reconstruct the crime scene.

5. Determining Distance Blood Falls
Blood drops fall as small spheres

6. Determining Distance Blood Falls
 Drops form circle when hitting surface
 Size depends on speed of blood drop

7. Determining Distance Blood Falls
 Drops form circle when hitting surface
 Size depends on speed of blood drop
 Blood drops fall as small spheres
• Faster drop = larger diameter (size) , Higher distance = larger
diameter

8. Determining Distance Blood Falls
Faster drop = larger diameter (size)
Higher distance = larger diameter
Due to air resistance, speed maxes out at
distances above about 7 feet

9. Determining Distance Blood Falls
However, size of drop also depends on the
volume of the drop.
Volume depends on the object blood
originated from (needle = small; bat = large).

10. Effect of Surface
 Smooth surface = smooth sphere
 Rough surface may cause some splatter

11. Determining Direction of Blood
 The angle can be determined
mathematically.
 Width/Length, then take the
inverse sin (sin-1).
 This number is the impact
angle (90 = perpendicular to
surface; <10 at a sharp angle)

12. WHAT IS A PATTERN
 A pattern is a group of individual spatters generated by
the same impact or applied force.
 The first step in determining the victim’s location is
recognition of a pattern.
 Pattern is influenced by a number of factors like
velocity of the impacting force, the directionality of
the applied force, the physical characteristics of the
wound providing the blood source, surface textures,
and obstructions presented by the external
environment.

13. Direction
of blood
The longer the
blood stain the
lower the angle
of impact
Spatter
diameter
increases with
height + spikes
appear at edge
of stain

14. Angle of impact
Example

15. POINT OF ORIGIN
 The area of origin is the area in three-dimensional space
where the blood source was located at the time of the
bloodletting incident.
 The area of origin includes the area of convergence with a
third dimension in the z direction.
 Since the z-axis is perpendicular to the floor, the area of
origin has three dimensions and is a volume.
 Determining the area of origin combines the two
dimensional area of convergence plus the angle of impact
determination for each of the selected stains.
 Angle of impact adds the third dimension to the point of
convergence determination, creating a spatial representation
of the location of the blood source.
 The area of convergence shows a victim location in a given
room or area, and the area of origin provides information
about their relative posture i.e. Standing, kneeling, or lying
down

16. Point of Origin of Stain
pattern (3D)

17. METHODS OF AREA OF ORIGIN
DETERMINATION
 STRINGING METHOD
 TRIGONOMETRIC METHOD
 GRAPHIC MEHTOD
 COMPUTER PROGRAMS

18. The stringing
method
Used to determine point
of convergence of several
blood spatter stains (i.e.
location of the victim)
After measuring the width &
length of the blood spatter a
simple calculation can be
done to determine the angle
of impact.

19. Area of convergence
(2D origin of spatter)

20. 2 methods to calculate point of origin (3D)
trigonometric and graphic method
Both methods need these initial steps at the
crime scene:-
1. Identify stains that have a common area of convergence
2. Draw lines along the central axis of each stain to
determine location of convergence
3. Measure the distance from the back edge of the stain to
the area of convergence
4. Calculate the angle of impact for each stain individually
5. Ensure at least 3 stains are used (the more the better)

21. Method 1 - TRIGONOMETRIC METHOD
Example:
If D = 30cm & i = 35o
H = tan35 x 30
H = 21cm

22. Method 2 - GRAPHIC METHOD
Distance
to PoC
Angle of
impact
Stain 1 8cm 68o
Stain 2 16cm 52o
Stain 3 23cm 41o
1. X-axis represents the location of
the blood stain (eg. floor)
2. Z-axis represents the height
from the stain
3. Both axes must be drawn using
the same scale
4. Mark on the x-axis the distance
to the point of convergence for
each individual stain
5. Use a protractor to draw a line at
the angle of impact from the
mark on the x-axis until it
touches the z-axis
6. The area on the z-axis that the
lines converge will be the likely
point of origin

23. IMPACT SPATTER AND MECHANISMS
 After bloodstain pattern has been identified as spatter
based on the size, shape, or distribution of the stains, it
is frequently possible to further classify the patter as
impact spatter as beating, stabbing, gunshot, power tool
or explosive events.

24. TYPE OF SPATTER
 Gunshot spatter
 Beating and stabbing spatter
 Satellite spatter
 Castoff pattern
 Expirated Bloodstain Pattern

25. Gunshot Spatter
• Gunshot spatter can result in a mist-like
spatter that indicates a gunshot.
 Not all gunshots will result in misting.
 If misting is present, it is most likely a
gunshot.
 Gunshots result in back spatter (where bullet
enters) and forward spatter (where bullet exits).

26. Beating and Stabbing Spatter
• Beating and Stabbing Spatter = larger
individual stains
• First blow usually doesn’t result in spatter
since there is not yet any exposed blood.

27. Satellite Spatter
• Satellite Spatter = free falling drops of blood
that fall onto a spatter pattern.
 These drips are usually much larger than
impact spatter.
 However, blood dripping into blood can
create a spatter.

28. Castoff Pattern
• Castoff Pattern = Blood flung off of
swinging object.
• Can reconstruct where assailant and victim
were positioned.

29. Expirated Bloodstain Pattern
• Expirated Bloodstain Pattern = Blood can
accumulate in lungs, sinuses, and airway.
Forcibly exhaled.
 Can appear like beating or gunshot pattern.
 May be mixed with saliva or nasal secretions.

30. THANK YOU