Bloodstain Pattern Analysis
Number of blows struck is determined by...
# of linear patterns and adding 1 to the sum
High Velocity Impact Spatter (HVIS)
*considered to be 100ft/sec and greater and travels a maximum of about 4ft horizontally *ex: gunshot *velocity of the impact force & not the velocity of the blood spatter that is associated with these terms *0.1mm diameter
What type of bloodstains do smooth surfaces vs irregular surfaces vs absorbent surfaces make?
*smooth surfaces: round bloodstains *irregular surfaces: irregular shaped bloodstains *absorbent surfaces: smaller diameter stains
How much blood does an average body contain? Water?
4.5-5 liters 90%
What percent of HVIS is found from gunshot wounds in an individual's hand occurs? with what type of a handgun
40%; .38 caliber or larger
How long does clotting take to begin?
6-8 minutes
blood Is _____ as viscous as water
6x
Elongated Stains
Blood drops impacting surfaces at angles less than 90 degrees
Points of Origin and Convergence assist the investigator in...
Determining the source location for a particular stain.
Low Velocity Impact Spatter (LVIS)
Dripping blood, the result of the force of gravity alone. 3mm+ diameter
Why is blood red?
Due to dissolved oxygen
True or False: Beyond 7 feet in height, there will be increase in stain diameter.
False
True or False: The absence of blood on hands of suspects eliminates them as suspects.
False.
True or False: A blood drop dries from the middle first.
False. From the outside edges.
True or False. HVIS travels the most distance compared to MVIS & LVIS.
False. The least amount of distance.
Medium Velocity Impact Spatter (MVIS)
Range of 25ft/sec. Blunt force trauma (1-3mm diameter).
Is the phrase, blood "spatter" or blood "splatter"?
Spatter
What shape is blood in flight?
Spherical
Splatter
The action involved in spreading the blood
Spatter
The result of a force impacting a source of blood
True or False: Aspirated blood often mimics HVIS in appearance.
True
True or False: It is virtually impossible for multiple cast-off stains to exactly overlap each other.
True
True or False: The more absorbent a surface is, the smaller the resultant stain.
True
True or False: There is more cast-off blood at the termination of the back stroke than on termination of the front stroke.
True
cast-off stains
blood that has been thrown from a secondary object (weapon or hand) onto a target other than the impact site. linear
Does blood get darker or lighter as it dries?
darker
Why does blood darken as it dries?
due to loss of oxygen
Terminal velocity
gravity & air friction acting upon blood drops
The larger the drop, the ______ of the stain diameter
greater
As the distance that a blood drop falls from increases, the stain diameter ______ of about __ feet
increases; 4
Bloodstain patterns are _____ ________ to the force that created it.
inversely proportional
The larger the blood drop, the _____ the stain diameter is
larger
Between 4-7 feet in height, very ______ stain diameter differences may be detected
little
The smaller the angle of impact, the _____ the stain
longer
What is the liquid portion of blood? After clotting?
plasma; serum
Angle of impact formula
sin^-1(width/length)
The greater the force, the _______ the stain diameter
smaller