Forensics Blood Splatter Flashcards
Who discovered platelets
William Osler
Who created the first DNA profile
Alec Jeffreys
Who discovered there were different blood types
Karl Landsteiner
Who wrote the earliest reference to blood spatter analysis?
Dr. Eduard Piotrowski
What are the scientific names for red blood cells, white blood cells, and platelets?
erythrocytes (red blood cells), leukocytes (white blood cells), and the thrombocytes (platelets)
What is the function of red blood cells?
carry respiratory gases.
Oxygen and carbon dioxide, made in the bone marrow, no nucleus
What is the function of white blood cells?
White blood cells fight disease and foreign elements.
Make in the lymph nodes, contain nucleus (DNA)
What is the function of platelets?
Platelets aid in blood clotting and help repair damaged blood vessels.
What percent of blood is composed of plasma?
55%
What type of evidence is blood?
Class Evidence
How is blood type specified?
by the presence or absence of certain antigens
What percent of the population has each blood type? How many are Rh positive?
Type O (43%)
Type A (42%)
Type B (12%)
Type AB (3%)
hat happens when incompatible blood types are mixed?
your body produces antibodies to destroy the donor’s blood cells
What antigens and antibodies are associated with each blood type?
Type O: Anti A/B
Type B: Anti B
Type C: Anti A
Type AB: nil
Who can each blood type donate to and receive from?
A Receive: A,O
A Donate: A, Ab
B Receive: B, O
B Donate: B, Ab
AB Receive: A, B, AB,O
AB Donate: AB
O Receive: O
O Donate: A, B, AB, O
What did Balthazard do?
was the first researcher to analyze the meaning of the spatter pattern (1939)
What case was blood spatter evidence used by the defense?
blood spatter evidence was used by the defense in the Sam Sheppard case
What things can be determined from analyzing a blood spatter pattern?
help recreate a crime scene.
exclude suspects
How many people were there
What are adhesion and cohesion, and how do they affect blood drops?
adhesive forces between a liquid and a surface are stronger, they will pull the liquid down, causing it to wet the surface. However, if the cohesive forces among the liquid itself are stronger, they will resist such adhesion and cause the liquid to retain a spherical shape and bead the surface
What are satellites?
When blood falls from a height or at a high velocity, it can overcome its natural cohesiveness and form satellite droplets.
What are spines?
When it falls onto a less-than-smooth surface, it can form spiking patterns around the drops called spines.
What is meant by the directionality of blood?
The shape of an individual drop of blood provides clues to the direction from where the blood originated.
Describe the characteristics of a blood drop that shows directionality.
A drop of blood that has a circular shape (equal width and length) indicates that the blood fell straight down. (as an example
List and describe the 3 categories that blood stains can be classified in.
Passive – created due to gravity acting on the blood
olume, and flow)
Spatter – involve a force in addition to gravity, and show directionality and distribution of blood
Altered - stains that have been physically or physiologically changed
