Forensics & Genetics Unit 4: Blood (8.4-8.6)

blood evidence can tell:

• who was there

• when the crime occured

• the positions/movement of the victim or assailant

• type of weapons used

How many people should be allowed in to the crime scene?

limited amount

Should protective wear be worn by investigators?

yes

Why should bloodstian evidence be kept away from sunlight

prevent bacterial growth

Do CSI’s gather infomation or collect evidence first?

gather information

types of information CSI get:

• eyewitnesses

• reading suspects’ statments

• information from the first responder/detective

examinimg wounds

can help tell the size/location of the injury

What can blood trails show?

movment of the suspect

What can transfer patterns show?

direction of travel

number of people

possible identification

What can void patterns show?

• somone else being present

• furniture being moved

What can arterial gush show?

if the person has a large injury

What can expired blood/air bubbles show?

possible internal bleeding

What can cast off patterns show?

to see if an object was in motion

What can hair swipe show?

which direction the body was dragged

What can the size of blood splatter show?

shows velocity and the type of weapon that was used

What can blood found on objects show?

• they were present during the time of the crime scene

• object could have handled by the subject

What do CSI’s use to document evidence?

• note taking

• videotaping

• still photographs

• sketches

What will happen if there is no visible blood at the crime scene?

investigators will use luminol

luminol

detect trace bloodstains at crime scenes by reacting with iron in hemoglobin, even after cleaning

Where is all the evidence logged?

chain of cusotdy

What can blood analysts be?

law enforcement

• labatory staff

pattern analysis

examination of the physical characteristics

(size, shape, distribution, and overall appearance)

crime scene reconstruction

based on physical evidencesuch as the angle of imact, area of convergence, area of origin, and blood spatter pattern

chemical testing

ELISA test: used to confirm if the blood is human

human blood: the sample will change color

not human blood: the sample will not change color