CHAPTER 8. BLOOD TYPING

Forensic Science I

Chapter 8. Blood and Blood SpatterObjectives and Vocabulary

Objectives Explain the composition of

blood Describe the functions of

blood cells Describe a brief history of the

use of blood and blood spatter in forensics

Describe how to determine the blood type of a sample of blood

Calculate the probability of certain blood types within a population

Conduct a blood spatter analysis

Examine stab wounds and describe the nature of the weapon

Use blood spatter evidence to recreate the events of a crime scene

Vocabulary Agglutination Antibodies Antigen-antibody response Antigens Cell surface proteins Lines of convergence Point of origin Red blood cells Satellite drop of blood White blood cells

Chapter 8. Blood and Blood SpatterBlood Paints a Picture

1. Why did the police suspect that the wife did not fall and injure herself?

2. What would they need to find out about the bloodstain on the husband’s sleeve to validated their suspicions?

3. Was there other evidence the police could use to prove or disprove the husband’s story?

Chapter 8. Blood and Blood SpatterIntroduction

Blood typing, class evidence Type O Type A Type B Type AB

DNA DNA is found in white blood cells

Blood spatter Note the direction the blood originated The angle of impact Point of origin Low or high velocity impact Type of weapon used

Chapter 8. Blood and Blood SpatterBlood History

Blood has been studied in one way or another for thousands of years (See Figure 8-1)

Chapter 8. Blood and Blood SpatterComposition

Circulating Tissue made up of three types of cells Red blood cells

(RBC) White blood cells

(WBC) Platelets

Cells are suspended in liquid called plasma

Chapter 8. Blood and Blood SpatterBlood Cells

Red Blood cells Erythrocytes Carry respiratory gases Hemoglobin in red blood cells,

carries oxygen, gives blood its color

White Blood cells Leukocytes Fights disease and foreign

invaders Antibodies, secrete proteins Contain a nucleus

Platelets Thrombocytes Aid in blood clotting Help repair damaged blood

vessels

Chapter 8. Blood and Blood SpatterBlood Cells

Red Blood Cells 5-6 million

White blood cells 5,000-10,000

Platelets 250,000-400,000

Chapter 8. Blood and Blood SpatterBlood Typing

Blood typing is less expensive and quicker than DNA profiling

Considered class evidence because many people share the same type

Can link a suspect to the crime

Chapter 8. Blood and Blood SpatterDiscovery of Blood Types

1900, Karl Landsteiner Blood from one person

did not always freely mix with blood from another person

The presence or absence of cell surface proteins gives rise to our present system of blood typing.

Use an antibody reaction test

Chapter 8. Blood and Blood SpatterA and B proteins

A and B proteins are found on the surface of some red blood cells A proteins – A Blood B proteins – B Blood A and B proteins –

AB Blood No proteins – O

blood

Chapter 8. Blood and Blood SpatterA and B proteins

Percentage of the U.S. population Type O (43 %) Type A (42 %) Type B (12%) Type AB (3%)

Probability and Blood Types, pg 201

Chapter 8. Blood and Blood SpatterRh Factor

1940, Alexander Wenier- Discovered the Rh Factor

85% of the population has a protein called Rh factor , Rh+

Blood that does not have the protein is called Rh-

Chapter 8. Blood and Blood SpatterNaming of Blood Types

Based on presence or absence of the AB and Rh proteins

Difference of blood types was not discovered until 1901.

Antibodies will cause the blood to clump and may cause death.

Universal accepter

Universal donor

Chapter 8. Blood and Blood SpatterAntibodies

B-lymphocytes secrete antibodies Recognizes foreign

invaders Antibodies bind to

a the molecular shape of an antigen

Chapter 8. Blood and Blood SpatterAntigen-Antibody Response

Antigen-antibody response, when a foreign invader is recognized by the immune system

May be viruses, bacteria, or even the red blood cell protein from a person with a different blood type

Chapter 8. Blood and Blood SpatterAgglutination

Agglutination, when one arm of the y shaped antibody attaches to the red blood cell and the second arm attaches to another red blood cell

Could produce a clot in the blood vessel , will result in loss of gas exchange

Chapter 8. Blood and Blood SpatterBlood Typing Tests

Blood Typing http://nobelprize.org/

educational_games/medicine/landsteiner/index.html

C.S. #1-Ludwig Tessnow- 1901 Dismembered bodies of an eight and

six year old were found in the woods near their home.

Tessnow was a suspect and had blood on his clothes and boots. Told police they were from wood dye.

Based on blood test created by Paul Ihlenhuth--- found that he was guilty from the blood stains. Distinguish between animal and human

blood as well as other stains. Executed in prison.

C.S. #2-Thomas Zeigler 1975 Christmas Eve , found his wife, her

parents and citrus worker were found dead in his store.

Claimed that a gang attempted to rob the store.

However when a blood expert came in to examine the bodies, they figured out that Thomas did it.

Sentenced to life in prison.

Graham Backhouse ( 1985)-- accused of killing his neighbor and attempting to kill his wife. Claimed that the bomb was from his neighbor. When police got to the house, found that the neighbor was shot with gunshots. Backhouse had sustained wounds to the face and chest. Backhouses wounds were self inflicted from the blood spater. Backhouse was convicted of murder of his neighbor and the attempted murder of his wife.

C.S. #3-Graham Backhouse 1985 Accused of killing his neighbor and

attempting to kill his wife. Claimed that the bomb was from his

neighbor. When police got to the house, found

that the neighbor was shot with gunshots.

Backhouse had sustained wounds to the face and chest. Backhouses wounds were self inflicted from the blood spatter.

Backhouse was convicted of murder of his neighbor and the attempted murder of his wife.