Daily Trivia
• Women blink nearly twice
as much as men.
Agenda
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DT
Agenda
Bloodstain Notes
Classwork
Homework
Forensic Science
BPA
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• Bloodstain Pattern Analysis
How can an investigator use bloodstain patterns to analyze
a crime scene?
Location and description of individual stains and patterns
Direction a blood droplet was traveling by calculating angles
of impact
Area of origin of blood source or sources
The type of object used in attack (edged, blunt, firearm, etc.)
Minimum number of blows
The positions of the victim, suspect, and objects during events
The sequence of events
Bloodstain Pattern Analysis Terms
• Spatter – Bloodstains created from the application of force to the
area where the blood originated.
• Origin/Source – The place from where the blood spatter came
from.
• Angle of Impact – The angle at which a blood droplet strikes a
surface.
• Parent Drop – The droplet from which a satellite spatter
originates.
• Satellite Spatters – Small drops of blood that break off from the
parent spatter when the blood droplet hits a surface.
• Spines – The pointed edges of a stain that radiate out from the
spatter; can help determine the direction from which the blood
traveled.
Passive Bloodstains
– Patterns created from the force of gravity
– Drop, series of drops, flow patterns, blood
pools, etc.
Single Trail
Multiple Trail
Pool
Projected Bloodstains
– Patterns that occur when a force is applied to the
source of the blood
– Low, medium, or high impact spatters, cast-off,
arterial spurting, expiratory blood blown out of the
nose, mouth, or wound.
Arterial Spurt
Radial
Cast off
High vs Low velocity
Transfer or Contact Bloodstains
– The pattern created when a wet, bloody object
comes in contact with a target surface; may be
used to identify an object or body part.
– Wipe pattern from an object moving through a
bloodstain or swipe pattern from an object
leaving a bloodstain.
Luminol
• Used to locate traces of blood, even if it
has been cleaned or removed.
• Only lasts 30 seconds.
• Also reacts to some metals, paints,
cleaning products and plant matter.
• Can destroy other evidence in the crime
scene.
• For this reason, investigators only use
luminol after exploring a lot of other options
Homework
• Bloodstain Pattern WS