Please enable JavaScript.
Coggle requires JavaScript to display documents.
Bloodstain Pattern Analysis The Science of Crime Scenes (2018) Chapter 7…
Bloodstain Pattern Analysis
The Science of Crime Scenes (2018)
Chapter 7.2
Directionality
behavior of traveling blood can be compared to a
ball of thin pancake batter
motion in the 45-degrees example gives rise to a “tail”
can
tell which direction the bloodstain was traveling when it hit the target
high-speed photography that blood droplets in
flight are in the form of spheres
Grouping Bloodstains
location
tails
indicate that the blood droplets were traveling in an 8 o’clock to 2 o’clock direction
size
group of same size drops indicates likely same event
shape
group of similar shape drops indicates likely same event
Droplet Size and Force
Greater force = Smaller size predominate droplet.
high-velocity or high-energy spatter
droplets 1mm and smaller in diameter
Medium-velocity
cause: medium force event (stabbing, beating)
1-4mm diameter bloodstains
Low-velocity
cause: low-force event (nose bleed)
4mm and larger bloodstains
Types of Bloodstains
Passive
produced by gravity.
ex: drips, splashes, flows, pools
Impact Spatter
result of an impact from an object to a blood source
forward and backward patterns can be produced
Transfer Stains
wipes, swipes, contact/pattern transfer stains
Wipe - object moves through preexisting bloodstain
Swipe - bloodied object moves across blood to a target
Contact/Pattern transfer: wet bloody object contacts another surface.
Latent
not visible, need chemical enhancement to see
Other
projected
from arterial spurts/gushes
cast-off
blood released from or projected onto a surface from moving object
expirated