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