Forensic sciences

3 things we can determine from blood evidence

• DNA

• type of weapon

• left or right handed

• location of the victim / assaltor

• # of victims / assaltans

Angle of impact

sin0=w/l

Skeletonied blood stain

a bloodstain pattern that can arise if a blood drop is allowed to partially dry and is then wiped

Expiratory blood

intenal injuries

Arterial spurts

blood released when a major artery is severed

Satelite bloodstain

smaller bloodstain that originated during the formation of the parent stain as a result of blood impacting a surface

wipe

an altered bloodstain pattern resulting from an object moving through a wet bloodstain

voide

when a person or object blocks the path of the blood

Criminal

• no guilty

• beyond resonable doubt

• didn’t testify

• glove didn’t fit

• mistake by prosecutor

  • poor sample handeling (custody)

Civil

• guilty

• most likely responsble

• 9/12

• have to testify

• guilty- shoes

Touch DNA

can’t see it, have verry little

PCR

copies DNA

STR

methode hoe we compare DNA samples

YSTR

looking for male DNA + paternity

Hair

can have DNA only in the root

Common DNA on scene

• blood

• semen

• weapon handle

• fingernail clippings

Collin Pitchfork

1st to be prossecuted on DNA evidence

Snow ball the cat

got his owner caught