Produced with more energy or force than gravity
The force of the impact causes the blood to break into smaller size spatters relative to the amount of force applied
This type of spatter is usually seen in blunt force, stabbings, and secondary spatters
Produced when the majority of larger drops of blood are broken into smaller spatters with diameters of 2 – 4 mm
The force associated with this type of spatter is greater than 25 ft per second
Impact spatter that measures less than 2mm in
diameter
The force necessary to produce this size spatter
is greater than 100 ft per second
This type of spatter is usually associated with
gunshots, explosions, and high speed collisions
High Force Impact Spatter takes on a "mist like"
appearance
What kind of information can you obtain from a
blood stain analysis?
What kind of facts can the a properly documented bloodstain pattern found at a crime scene confirm or refute?
Which is the main characteristic of blood flight?
Name 2 kind of bloodstain
a) 1. Distance from the blood source to the target
2. Direction of travel and impact angles
3. Nature of the force used to cause the bloodshed
4. The object used to cause the bloodshed
5. Sequencing of multiple bloodshed events
6.Interpretation of contact or transfer patterns
b) 1. Confirm or refute the position of a victim, witness, suspect, or defendant
2. Determine if there is evidence of a struggle, or if the assault is "one sided"
3. Confirm or refute statements made by principles in the case
BLOODSTAIN PATTERN ANALYSIS
A CASE STUDY
IMPACT SPATTERS:
are a random pattern of spatter of varying sizes
It is important to note that the term "Velocity" does not measure the speed at which the blood is
traveling, but rather is used to describe or measure amount of force applied to the blood, to cause it
to spatter.
HIGH FORCE (VELOCITY)
IMPACT SPATTER:
MEDIUM FORCE (VELOCITY) IMPACT SPATTER:
OR PROJECTED SPATTER
Transfer - Swipe Pattern
LOW FORCE (VELOCITY) IMPACT SPATTER/PASSIVE DROPS:
Blood that falls at the speed or force of normal gravity.
These spatters usually fall from an open wound, or from a
surface that is saturated with blood.
The majority of the Low Force Impact Spatters are large,
circular, spatters with diameters of 4mm or more.
Low Force Impact Spatters will increase in size as the
distance fallen increases, however, the size of the spatters
will remain constant after approx 4 feet.
Spatter Pattern
Angle of Impact:
The steeper the impact, the more
elliptical or elongated, the blood drop
Transfer - Wipe Pattern
1. Distance from the blood source to the target
2. Direction of travel and impact angles
3. Nature of the force used to cause the bloodshed
4. The object used to cause the bloodshed
5. Sequencing of multiple bloodshed events
6.Interpretation of contact or transfer patterns
TAKE THE QUIZ
Bloodstain Pattern Analysis
SPATTER VS TRANSFER
Direction:
The "tail" points to the direction of
the blood drop
is the examination of the shapes,
locations, and distribution of patterns of bloodstains, in order to provide
an interpretation of the physical events that gave rise to their origin.
The simplest type of blood spatter analysis is determining
spatters from transfers.
1)Spatters are created when blood is acted upon by force, and travels through the air before landing on a target surface.
2)Transfers occur when a blood source comes in direct contact with a target surface area.
The following Information may be obtained from a
proper Bloodstain Pattern Analysis:
Blood Flight Characteristics:
When properly documented, bloodstain patterns found at the crime scene, or on a
particular person's clothing, can be used to:
- Blood will not break up unless it is acted upon by force. The force must be great enough to overcome the surface tension of the blood
- Blood forms a spherical shape (perfect circular shape) almost immediately upon separating from the blood source. The spherical shape is caused by the surface tension of the blood.
- Surface Tension causes the blood drop to pull itself in; both horizontally and vertically.
- The blood drop will settle into a spherical shape, as a result of the surface tension.
- The surface tension will maintain the sphere shape of the blood drop until it impacts with the surface.
1. Confirm or refute the position of a victim, witness, suspect, or defendant
2. Determine if there is evidence of a struggle, or if the assault is "one sided"
3. Confirm or refute statements made by principles in the case:
IE: Are stain patterns on a particular person's clothing consistent
with accounts given by the victim, witness, or defendant?
c)surface tension