Blood Spatter
What formula do you use to measure the angle of impact?
AOI = SIN-1 W / L ● W - Width of blood drop ● L - Length of blood drop
Blood type O will have
Anti A and Anti B antibodies
Determine blood type?
Antibody test
As droplet moves --------- from source, it elongates and may produce a --------
As droplet moves away from source, it elongates and may produce tail ● Tail points in direction of blood's movement ● Satellites or secondary drops may appear in front of moving droplet of blood
A passive fall is when
Blood falls directly to floor at 90-degree angle will produce circular drops, with secondary satellites being more produced if surface hits is textured
Confirm the stain is human?
ELISA test (enzyme-linked immunosorbent assay) This is a test that detects and measures antibodies in your blood. This test can be used to determine if you have antibodies related to certain infectious conditions.
Properties of blood inlcude
Gravity, cohesion, adhesion, surface tension
what else is in plasma besides water?
-dissolved proteins (antibodies, hormones, clotting factors) -nutrients (O2, glucose, amino acids, salts, minerals) -wastes (urea and O2)
Types of blood spatter
-passive fall - arterial spurts or gushes -splashes -smears - trails -pools
on a Flat surface.....
... the edge of blood drops appears smooth and circular ● Glass, marble
The universal donor blood type is
O
Medium-Velocity Impact (25 ft/sec)
Size - 1-4 mm ● Ex. - beating, stabbing
Low-Velocity Impact (5 ft/sec)
Size - 4 to 6 mm ● Ex - blunt object impact (hammer, flashlight, etc)
Formula for POPO =
TAN (AOI) x y
How can you confirm if a stain is blood?
Visualization with Luminol- you apply luminol to something and put it under a black light. If the stain is blood, it will appear blue Kastle-Meyer test-the chemical indicator phenolphthalein is used to detect the possible presence of hemoglobin. You put the phenolphthalein on a q tip and go to town.
Blood type B will have
anti A-antibodies
blood type A will have...
anti B-antibodies
platlets help...
blood clotting
Cohesion:
blood mixture is attracted to similar blood mixtures and sticks together, not separates, as it falls ● Causes droplet to stay together
Why would you blood type over DNA profiling?
blood typing is less expensive and quicker
red blood cells are produced in
bone marrow
white blood cells are also produced in
bone marrow
Trails
can be left by bleeding victim depositing blood as he or she moves from one location to another. ● Can be round, smeared, appear as spurts
red blood cells...
carry gasses
on a porous surface....
edge of drop of blood may form small spikes (extensions) or satellites ● Spikes - attached to main droplet ● Satellites - not attached to main droplet
Circular drop (width = length)
fell straight down ● Typical of dripping wound (passive)
white blood cells
fight diseases and foreign invaders
High Velocity Impact (100 ft/sec)
fine-mist spatter pattern ● Size of Droplets - less than 1 mm ● Ex. Gunshot wound
Pools
form around victim who is bleeding heavily and remains in one place. If victim is moved to another location, there may be droplets or smearing connecting the first location with a second
Lines of Convergence
found by drawing straight lines down the long axis of blood spatter and noting where they intersect
white blood cells are true cells because they....
have nucleuses
hemoglobin is....
iron containing proteins that bind to O2. They give blood there color.
the universal blood type recipient is...
is AB
Who discovered blood type?
karl Landsteiner
Smears
left by bleeding victim depositing blood as he or she touches or brushes against a wall or furniture ● transfers
Point of Origin
lies at a point in space above the point of convergence. ● Measurement of the impact angle allows for translation of the 2-D image (convergence) into a 3-D one (origin).
red blood cells don't have a...
nucleus or any other organelles
Throbocytes
platelets
Elongated drop (width < length)
possible to determine direction blood was traveling
Gravity:
pulls it to ground ● Droplet becomes longer than wide
Rh factor is when...
red blood cells have a RBC protein. It is particularly important as a cause of hemolytic disease of the newborn and of incompatibility in blood transfusions.
Ehythocytes
redblood cells
Splashes
shaped like exclamation points. ● Shape and position of spatter pattern can help locate the position of the victim at the time of the attack
kastle Meyer test invloves
taking a wet cotton swab with distilled water and gently rubbing on the stain. Ethyl alcohol breaks open the cells and exposes the hemoglobin. Phenolphthalein turns pink when oxidized. Hydrogen peroxide reacts with hemoglobin. If blood is present the swab will turn pink.
Adhesion:
the action or process of adhering to a surface or object. ● starts as teardrop because of adhesion
ANGLE of IMPACT
the acute angle formed between the direction of the blood drop and the plane of the surface it strikes.
Surface Tension:
the elastic like property of the surface of the liquid that makes it tend to contract, caused by the forces of attraction between the molecules of the liquid. ● Formation of a sphere
Blood splatter analysis
the examination of the shapes, locations, and distribution patterns of bloodstains, in order to provide an interpretation of the physical events which gave rise to their origin
Arterial spurts or gushes
typically found on walls or ceilings caused by pumping action of the heart
90% of plasma is...
water
Area or Point of Convergence (POC)
where lines meet or intersect
leyocytes
white blood cells
Properties of Blood Volume
(fun)
A blood loss of _____ liters, internally or externally, is required to cause incapacitation.
1.5
Location of the source of the blood can be determined with at least....
2 drops of blood spatter
_________ liters of blood for females
4 to 5
A __________ blood volume loss, internally or/and externally, is required to produce irreversible shock (death).
40 percent
Cells make up...
45% of blood
_________ liters of blood for males
5 to 6
plasma makes up...
55% of blood
On average, blood accounts for ___ of total body weight
8%
What can you determine from blood spatter?
1. Origin(s) of bloodstain 2. Distance of bloodstain from target 3. Direction from which blood impacted 4. Speed with which blood left its source 5. Position of victim & assailant 6. Movement of victim & assailant 7. Number of blows/shots