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Transcript of Blood Spatter
From bloodstains, we can tell:
Types of Bloodstains
Bloodstain pattern(s) resulting from blood exiting the body under pressure from a breached artery
Systole (contraction/pumping) vs. Diastole (relaxation/filling)
Blood that is blown out of the nose, mouth, or a wound as a result of air pressure and/or air flow which is the propelling force
Blood directed back towards the source of energy or force that caused the spatter
Often associated with entrance wounds
The velocity of blood can lead to different types of patterns on the walls. These are usually identified by the amount and size of the droplets.
High Velocity Impact Spatter
Caused by a high velocity impact or force to a blood source.
Most often caused by gunshots or high speed machenery.
Medium Velocity Impact Spatter
Caused by a medium-velocity impact, or force, to a blood source.
Normally caused by a beating.
Low Velocity Impact Spatter
Pattern caused by low velocity impact, or force, to a blood source.
Evidence that blood has come into contact with a surface
A pattern-bearing group or distribution of bloodstains created through regular or repetitive form, order, or arrangement.
Properties of Blood
Surface tension: the force that pulls the surface molecules of a liquid towards its interior
Viscosity: Resistance to flow
victim's or accused's movement and position at the time of the incident
point of origin
number of times the victim was injured
possible weapon(s) used
time that the crime occurred
Blood which travels in the same direction as the source of energy or force which caused the spatter
Rings in blood that result when blood containing air bubbles dries and retains the bubble's circular configuration as a dried outline
Definition: fluid that circulates in the heart, arteries, capillaries, and veins of a vertebrate animal carrying nourishment and oxygen to and bringing away waste products from all parts of the body
Ways to visualize blood
Visibility vs. invisibilty.
Draw Back Effect
When blood is present in a firearm and is drawn back into the muzzle.
A bloodstain pattern created when blood is released or thrown from a blood-bearing object in motion.
The shape and direction of a bloodstain due to gravity or movement of the object.
Cast off demo!
An absence of stains in an otherwise continuous boodstain pattern.
When blood has been reduced to a fine spray as a result of the energy of the force that was applied to it.
Also characteristic of a gunshot and similar in size to high-velocity.
Pointed or elongated stains which radiate away from the center of a bloodstain
Help indicate directionality
The direction and angle of bloodstains can provide a lot of information to investigators.
The angle between the long axis of a bloodstain and a predetermined line on the plane of the target surface, which represents 180 degrees
Angle of Impact
The acute angle formed between the direction of a blood drop and the plane of the surface it strikes
Area of Convergence
Area of Origin
The common point in three dimensional space to which the trajectories of several blood drops can be retraced
A bloodstain pattern resulting from a liquid that dripped into another liquid (one of which is blood)
Satellite spatter originates from parent drop or stain
A bloodstain pattern created when blood receives a blow or force resulting in the random dispersion of smaller drops of blood
The transfer of blood from a moving source onto an unstained surface
Direction of travel may be determined by the feathered edge
A bloodstain pattern created when a wet, bloody surface comes into contact with a second surface
A bloodstain pattern created when an object moves through an existing stain, removing and/or altering its appearance
A bloodstain that, although disturbed, still reflects its original shape and size
Consists of only its outer periphery, the central area having been removed by wiping or flaking
Also referred to as skeletonization
A bloodstain resulting from the accumulation of liquid blood in an absorbent material.
Essentially what happens when blood gets onto clothes and can still be seen, even after it was washed.
A bloodstain pattern resulting from a volume of liquid blood that falls or spills onto a surface
A bloodstain resulting from contact between a blood-bearing surface and another surface
Contact and swipe patterns are examples
Using all you leaned today, tell us as much as you can about the following two crime scenes.
May the odds be every in your favor.
Crime Scene #1
Crime Scene #2
Thanks for Listening!
What would cause a void?
The common point on a two dimensional surface over which the directionality of several blood drops can be retraced
Blood clots in 3-15 minutes, depending on various diseases and characteristics of the individual.
Clotting is used to determine how much time has passed since the blood has been shed.
A shiny, gelatinous pool indicates that less than an hour has passed.
Once the blood has separated into white blood cells & plasma (serum) and red blood cells, several hours have passed.
Passive clotting acts on only gravity while projected clotting is caused by forces other than gravity.
Slow moving blood clots before it gets too far away from the body. This coagulation around a wound can close up if the victim is still alive, leaving scabs and eventually scars.
dark blue discoloration
blood settling into parts of the body based on gravity
if blood is on the upper surface of a found body, what can you conclude?
How can you differentiate between lividity and a bruise?
What type of spatter would occur if a victim was stabbed in the neck?
impact spatter from force
cast off blood