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Bloodstain Pattern Presentation
I have an interest in this section of law enforcement for
three main reasons:
 The excitement of never knowing what is next,
something different is always occurring.
 Bringing justice to victims and answers to their
families.
 Science is constantly evolving, bringing new
innovations to crime solving.
I. As quoted by forensic scientist Dr. Henry C. Lee,
“Forensic science is used to predict not the future but
the past.”
a) Relying on evidence and its scientific analysis, forensic
science is an essential part of the criminal justice system.
Forensic science relies on a number of wide ranging
disciplines and methods in order to achieve its goals;
bloodstain pattern analysis is one small part of a much
larger group of individuals that come together for the
purposes of crime scene investigation.
b) Bloodstain pattern analysis is the examination of the
shapes, locations, and distribution patterns of bloodstains,
in order to provide an interpretation of the physical events
which gave rise to their origin.
c) This presentation will be a very, very brief look into
bloodstain patterns. We will go over a few different types
of bloodstain patterns and terms used in the analysis of
these patterns.
II. The shape and location of bloodstains provide clues
about where the victim and suspect were when the crime
took place and where they went afterward.
a) Information these patterns provide:
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Origin of the bloodstain
The type of instrument used
Direction from which a victim was struck
Relative positions of the victim, assailant or
assailants, and bystanders
 Location and movements during the attack
 Number of blows or gunshots the victim
received
 Test of truthfulness of suspects and witnesses
b) Categories of bloodstains:
1) Passive: Forms not because of force but because of
laws of gravity.
 Passive drop-blood drop created or formed by
force of gravity
 Drip pattern-a pattern which results from
blood dripping into blood
 Flow pattern-a change in shape and direction
of a bloodstain due to the influence of gravity
or movement
2) Transfer: Created when a wet, bloody surface comes
into contact with a secondary surface. Sometimes a
recognizable image of all or some of the original
surface can be observed in the pattern, such as a bloody
hand or footwear.
 Transfer/Contact
 Swipe-the transfer of blood from a moving
source onto an unstained surface
 Wipe-created when a object moves through
an existing stain, removing or altering its
appearance
3) Projected: Created when an exposed blood source is
subjected to an action or force, greater than the force of
gravity. The size, shape, and number of resulting stains
will depend, primarily, on the amount of force utilized
to strike the blood source.
 Low velocity impact spatter
 Medium velocity impact spatter-a beating
typically causes this type
 High velocity impact spatter-examples
would be a gunshot or high-speed machinery
 Cast-off-created when blood is released or
thrown from a blood bearing object in
motion
 Arterial spurting or gushing-pattern resulting
from blood exiting the body under pressure
from a breached artery
 Back spatter-blood that is directed back to
the source of energy or force that caused the
spatter
 Expiratory blood-blood that is blown out the
nose, mouth, or a wound as a result of air
pressure or airflow as the propelling force
IV. In conclusion, bloodstain pattern analysis involves the
study of blood spatters on walls, floors, furniture, and
other objects to determine the events that occurred at a
crime scene.
The goal of the reconstruction of the crime scene using
bloodstain analysis is to assist the overall forensic
investigation with the questions that must be addressed,
such as; what occurred, where it occurred, when and in
what sequence, who was there, who was not there, and
what did not occur.
Blood is one of the most significant and frequently
encountered types of physical evidence associated with
death and violent crime scene investigations. The analysis
of bloodstain pattern evidence is crucial in cases where
the manner of death is in question and the issue of
homicide, suicide, accident, or natural death must be
resolved.