Transcript Blood - Springtermforensics

Blood
By- Maya Ellerkmann and Abby
Boyer
Bloodstain Pattern Analysis
• 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 following Information may be obtained
from a
proper Bloodstain Pattern Analysis
• 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
When properly documented, bloodstain
patterns found at the crime scene, or on a
particular person's clothing, can be used to
• 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?
Blood Flight Characteristics
•
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.
SPATTER VS TRANSFER
• The simplest type of blood spatter analysis
is determining
spatters from transfers. Spatters are
created when blood is acted upon by
force, and
travels through the air before landing on a
target surface. Transfers occur when a
blood
source comes in direct contact with a
target surface area.
Transfer - Swipe Pattern
Spatter Pattern
Transfer - Wipe Pattern
TARGET SURFACE TEXTURE
• Bloodstains can occur on a variety of surfaces. The type of
surface that free falling blood strikes affects the
appearance of the resulting spatter.
• or regular circular shape.
• Blood drops on a rough surface will make an irregular
shaped stain with rough or jagged edges.
LOW FORCE (VELOCITY)
IMPACT SPATTER/PASSIVE
DROPS
MEDIUM FORCE (VELOCITY)
IMPACT SPATTER:
OR PROJECTED SPATTER
HIGH FORCE (VELOCITY)
IMPACT SPATTER
Angle of Impact:
The steeper the impact, the more
elliptical or elongated, the blood
drop
Direction:
The "tail" points to the direction of
the blood drop
Citations
• http://www.crimesceneforensics.com/Blood_Stains.html