Forensics Chapter 10: Bloodstain Analysis
Terms in this set (46)
Angle of Impact
the angle at which a blood droplet strikes a surface
the large pattern of blood that is created when blood escapes an artery under pressure; the increase and decrease in blood pressure is apparent
large patterns created under pressure, but with less volume and usually more distinctive evidence of blood pressure falling and rising
a mass of blood and other contaminants caused through clotting mechanisms
blood that has been thrown from a secondary object (weapon or hand) onto a large target other than the impact site
characteristic patterns present when blood drips into standing, wet blood
blood which is spattered onto a target, as a result of breathing, typically , this occurs when a injury is sustained to the throat, mouth, or airway
usually the point on the body that received the blow or applied force, from which the blood was shed
the point in space where the blood spatter came from
the droplet from which satellite spatter originated
blood under pressure that strikes a target
small drops of blood that breaks off from parent spatter when the parent droplet strikes s target surface
a pattern that helps to place an object or body in the scene; normally, the area in question lacks blood even though areas surrounding ti show blood
the pattern left when an object moves through a partially dried stain, removing part of the blood, but leaving outline of stain intact
bloodstains created from the application of force or energy to the are where the blood is
the pointed edges of a stain that radiate out to form the spatter
pattern created when a volume of blood in excess of 1 mL strikes surface ar a low to medium velocity
transfer of blood onto a target surface by a blood object that is usually moving laterally
the pattern created when a wet, bloody object comes in contact with a target surface leaving a pattern that has features of the object
surface where blood ends up
pattern created when a secondary target moves through an existing wet blood stain on some other object
when first research and analysis on blood spatter patterns began
blood spatter evidence was introduced for sam shepherd case
Dr Herbert and MacDonnell (1971)
first forensic experts who used blood spatter analysis as a modern day tool
origin, distance, direction, speed w/ blood left its source, position of victim/assailant, movement of victim/assailant, number of blows/shots
what does bloodstain evidence reveal?
passive (dripping), transfer (smearing) and projected
categories of blood stains
occur in shooting, trauma from blunt weapons, hacking or slashing attacks
blood trickles downward
until its weight is pulled by gravity
how long does blood drop grow?
tear drop shape
what shape does single drop make?
vertically and horizontally, resulting ing spherical shape
which way does surface tension pull blood drop?
single drop go blood falling from fingertip onto soothe cardboard from various heights
7 feet (1.2 m)
what height does diameter in blood spot stop changing?
what shape does splashes take on?
surface texture, direction of travel, impact angle, origin through point of convergence
dependent factors of blood stain patterns
blood falling from 90 degrees to flat surface will form what shape?
direction of travel
what does the tail of elongated stain tell us?
cast off spatter
low velocity blood spatter
medium velocity blood spatter
high velocity blood spatter
tiny blood satellites
method used at crime scene to determine origin of violent attack
location of wound, size of wound, distance
3 factors that effect backward spatter of blood
how long does it take for blood stain to skeletonize
point of convergence
the location of the blood surface source determined by drawing lines from the various blood droplets to the point where they intersect