Forensic Sci Unit 5 Blood Typing/Spatter

Agglutination (Definition)

Biological process where particles clump together in the presence of specific antibodies

Agglutination (Occurrence)

This occurs when antibodies bind to antigens on the surface of these particles, resulting in clumps

Universal receiver

AB+

Universal donor

O-

How to determine blood types (i.e. what test is ran)

ABO typing

→ Mixing blood with 3 anti-serums that react with each of the 3 proteins. If the serum clumps, the protein is present and you have it

Common blood type

O+

Rare blood type

AB-

Blood typing: Individual or Class evidence?

Class evidence because your own blood type can fall under a group, not specific to you alone (ex: Type A - many people have it)

Blood Spatter or Splatter?

Spatter

Luminol

Chemical that reacts with hemoglobin in blood and glows blue in black light to detect blood

Name of a person who studies blood spatter

Serologist

Wave Cast-Off

Tail of elongated stain points in direction of travel and back to parent drop

How would the appearance of a blood drop be affected by how far it fell?

It would be larger if it fell from a higher place

Blood drops on Smooth Surface

Perfect circles with smooth edges and no satellite droplets

Blood drops on Slightly Raised Surface

Circles with some satellite droplets

Blood drops on Rough Surface

Irregular shaped stain (not so much a circle) with rough or jagged edges

Point of Convergence (what is it + tells u)

…. tells us where the blood comes from

Location where the lines drawn through the long axis of several bloodstains meet. This point helps forensic analysts determine the origin of the bloodshed and provides insight into the height from which the blood originated

High Velocity (speed) blood spatter

Tons of dots

→ Most caused by Guns

Medium Velocity (speed) blood spatter

Some areas w/ larger blood spots + smaller blood spots

→ Hammer Strike

Low Velocity (speed) blood spatter

Very circle + small

→ Slow blood drops

Arterial Spurting

When high pressure blood sprays out with heartbeat