What three questions should the investigator answer when examining an apparent dried bloodstain?.

1.Is it blood?2.If so, animal or human?3.What is the blood type?

Define a presumptive test.

A screening test that presumes the presence of a substance.

What property of blood is used in most presumptive tests?

Hemoglobin-catalytic decomposition of peroxides to oxygen.

In your blood lab, what test was used to test whether a stain was blood or not?

The Kastle-Meyer test uses phenolphthalein reagent which reacts with the breakdown of hydrogen peroxide by the hemoglobin of blood and turns it a deep pink color.

What is a secretor?

A person whose blood antigens are found in other body fluids. About 80% of the population are secretors.

Define serology. How is it used in forensic investigations?

The study of body fluids using antigen-antibody reactions. Serologycan be used to exclude suspects.

How much blood is therein the average adult human?

4-5 Liters

What test can determine whetherblood is human or animal? What is the basis for this test? Why is the serum usedin this test called human antiserum?

The precipitin test. Specific antibodiesin an animal serum react to human antigens.

What are the four major blood types found in humans? Whatare the percentages of each in the U.S.A.?

A- 40%B-11%AB- 4%O- 45%

What is an antigen?

A protein found on the surface of a red blood cell that determine blood type.

What happens if a person with type AB blood is given a transfusion of type A blood? Explain.

There will be no adverse reaction because there are no antibodies to attack antigens.

To whom can a person with type B blooddonate blood and from whom can that personreceive blood?

He or she can donate to someone with B or AB blood and receive blood from someone with B or O.

Can a bloodstain be used for individualization?

Not with serology, but with DNA fingerprinting. Many of the blood factors begin to degrade immediately.

How does blood fall, in what shape and what causes it to fall that way?

A sphere and the surface tension of the blood causes to fall in that shape.

Can direction of travel be determined and if so, how?

Yes, direction can be determined due to the shape of the blood stain.

15. Calculate the angle of impact for the bloodstains below:

A- 19 degrees B- 26 degrees; C- 11 degrees D- 62 degrees; E- 49 degrees F- 37 degrees

Identify what may have caused these types of stains:

A is an arterial spurt

B is high velocity impact spatter

C is drop on an earlier drop

18. Sometimes a transfer pattern can indicate the weapon used in an assault. Guess what made the following:

A-brick or 2x4B-crowbar or pry barC-hammerD-fingerprintE-razor bladeF-monkey wrenchG-shirtsleeve with buttonH-a forkI-a knifeJ-scissorsK-corkscrewL- high heel from woman’s shoe.

Deduce what happened here:

A is a void, possibly the stem of a floor lamp B is a wipe pattern caused by a boot dragged across drops of fresh blood C is blood dripping from an object moving then stopping

What to study for the Chapter 10 Blood Exam.1.Notes2.All labs, worksheets, and quiz3.PowerPoint On-line4.Sam Shepard’s Case5.Chapter 10 in the Forensics book