Serology And Blood Pattern Analysis Flashcards
What is blood pattern analysis?
The examination of the size, shape and distribution of blood stains and patterns
What does blood pattern analysis address? (4)
What has occurred; when and in what sequence has that occurred; who was present; support/contradict statements given by witnesses, victims and POIs
What are bloodstains derived into?
Forced and non-forced
How do we determine the angle of impact of a blood stain?
Angle of impact = arcsin(width of stain/length of stain)
Blood is a non-Newtonian fluid. What does that mean?
As velocity increases it becomes more fluid like
What is serology?
The study of bodily fluids at crime scenes
What is serology based on?
The different proteins in different bodily fluids
What are the two tests in serology?
Presumptive and confirmatory
What is a presumptive test?
Highly sensitive but non-specific (can tell it’s blood but not what it’s from)
What is a confirmatory test?
Tests positive for the substance in question but only that substance.
What is blood?
A tissue comprised of several cells in a matrix called plasma
What can bloodstains be grouped into? (3)
Passive, transfer and projected/impact
What are examples of passive bloodstains?
Clots, drops, flies and pooling
What are examples of transfer bloodstains?
Wipes, swipes, pattern transfers and contact stains.
What are examples of projected/impact bloodstains?
Spatters, splashes, cast-off stains and arterial spurts
How do wipe stains occur?
When something moves through a blood stain
How do swipe stains occur?
When blood is transferred through a moving object.
How do spatter stains occur?
When blood hits a target.
How do cast-off stains occur?
When blood flies off a moving subject and stops suddenly.
How do voids occur?
When something comes between blood and the target.
What is a skeleton blood stain?
Occurs when blood partially dries but is then wiped. The original stain can still be clearly seen.
What blood cells are used for confirmatory tests?
Red
What blood cells are used for DNA testing?
White
