FSC239Y5 Lecture Notes - Lecture 5: Blood Falls, Surface Tension, Blood Residue
1. Lecture 3: Blood Stain Pattern Analysis
The study 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.
What can it determine?
oPoint of origin (where in the room it took place).
oType and direction of travel.
oMovement during and after bloodshed.
oMinimum number of blows/shots.
oEvidence of struggle.
oPosition of victim and/or suspect during bloodshed.
oIdentification of weapons used.
oCan confirm or refute witness or accused statements.\
Properties of blood:
o4 to 5 liters of blood in the human body.
oApproximately 8% of total body weight.
oPlasma makes up 55% of blood, remaining 45% are formed elements.
oPlasma – 91& water, 8% protein, 1% organic acids, 1% salts.
oFormed elements erythrocytes, leukocytes and platelets.
o40% blood volume loss, internally or externally required to produce irreversible
shock and death.
oBlood loss of 1.5 L, internally or externally required for incapacitation.
Principles:
oBlood behaves according to the laws of physics.
oBloodstain patters are predictable and reproducible.
oThe appearance of a bloodstain is surface dependent (need to know about
surfaces/easier with smooth flat surfaces as it won’t disrupt any information).
oDirectionality can be determined.
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