Serology and ForensicsSerology and Forensics

Blood TypingAnd

Blood Splatter Analysis

What is blood?What is blood?

• Blood is connective tissue. It is composed of a sticky fluid called PLASMA

• Plasma is mostly water but it also has other substances dissolved in the water.

• Plasma contains:• Proteins: antibodies, clotting proteins• Salts and ions: calcium, sodium chlorine

• Circulating wastes and nutrients: glucose, lipids, hormones, and wastes

40% of blood volume is actually occupied by cells

40% of blood volume is actually occupied by cells

• Leukocytes: only about 1% of the cells. Defend the body against invasion

• Platelets: fragments of bone marrow cells that help in blood clotting.

• Erythrocytes: Red blood cells. 5 billion of these cells in 1 ml of blood. • Shaped like a flat disk with a central depression on both sides.

• Hemoglobin carrying oxygen makes them red.

Who discovered blood typing?Who discovered blood typing?

In 1901, Karl Landsteiner reportedthat blood had TYPES.By matching thesetypes one could achieve success inblood transfusion.

How does blood typing work?How does blood typing work?

ABO Blood GroupsABO Blood Groups

• A reaction outside the body between like antigens and antibodies results in Agglutination where the blood cells clump together.

• A reaction within the body between like antigens and antibodies results in Hemolysis of the cells (they burst).

Blood TypingBlood Typing

• Blood typing detects sugars that act as recognition markers on the surface of our own erythrocytes (red blood cells, RBC’s).

• These sugars are recognized by our own immune system and are called cell surface antigens.

• There are THREE possible genes to code for the markers:

Three possible genes to code for the markers

Three possible genes to code for the markers

• Gene• 1A• 1B• 1i

• Sugar• A• B• No sugar

Since you can get ONLY ONE gene from each parent, each individual can only have two genes to code for the sugar markers.

Genetic possibilitiesGenetic possibilities

Mother

Father

A

O

B O

AB AO

BO OO

What are the possible Blood Groups ? ABO

What are the possible Blood Groups ? ABO

• TWO facts you need to know to interpret how the genes combine to give blood groups.• Gene 1A and Gene 1B are co-dominant. Both sugars are equal in their presence on the RBC’s

• Gene 1i codes for no sugar,so it is dominated by both 1A and 1B.

The Four Blood Types are:The Four Blood Types are:

Blood types Sugar Gene combinations A A 1A1A, or 1A1i

B B 1B1B, or 1B1i

AB Both A and B 1A1B

O None 1i1i

If someone has blood type AB, could one of their parents Have blood type O?

Blood Groups in average Population

Blood Groups in average Population

• The various ABO blood groups occur in the average population of the US show in the diagram to the left.

• These percentages vary with different ethnic groups.

Rh FactorRh Factor

• Discovered (1946) by Karl Landsteiner, Phillip Levine, and Alexander Weiner and their research on the Rhesus monkey, hence the name Rh factor.

• Three genes ( C, D, and E ) code for the Rh antigens present on the RBC cell membrane.

Rh FactorsBlood Types Based on Rh Factors

Rh FactorsBlood Types Based on Rh Factors

•Rh+ Rh antigens are present on the RBC’s

•Rh- Rh are not present on the RBC’s.

•85% of Americans are Rh+

More Rh FactorsMore Rh Factors

• Normally the plasma does not contain Rh antibodies.

• Rh negative individuals that receive Rh+ blood can have their immune system develop Rh antibodies that will remain in the blood.

Erythroblastosis fetalis(Hemolytic disease of the newborn)

Erythroblastosis fetalis(Hemolytic disease of the newborn)

• A Rh negative mother may be exposed to the Rh antigen from the blood cells of the Rh positive baby during pregnancy or at the time of birth.

• If the Rh+ blood cells enter the Rh- mother’ blood the mother’s immune system may become sensitized and produce antibodies against Rh+ blood antigens

• In subsequent pregnancies, these antigens may cross the placenta and causes the hemolysis of the Rh+ blood cells in the fetus.

What Happens and What Can Be Done?

What Happens and What Can Be Done?

• The Rh positive baby will become anemic.• This can be avoided by injecting the Rh negative woman with antibodies (RhoGAM) during each pregnancy and within 72 hours after birth of each Rh positive baby.

• The injection of antibodies into the woman inactivates the Rh antigens on those blood cells that might have entered the mother’s blood and prevents her body from activating her immune system.

How does blood typing work?How does blood typing work?

• Your blood is not attacked by your own immune system because the sugar markers are recognized by your own body.

• However, if a type A person receives a transfusion from a type B person, the Type A recipient’s immune system will recognize the type B RBC’s as foreign and attack.

AntibodiesAntibodies

• Antibodies are proteins that “tag” foreign markers for destruction. The foreign blood cells literally clump together as the antibodies attach to them.

• This clumping can be fatal in the body, but it is also the basis for typing blood.

+

Type B blood

Other ExamplesOther Examples

Blood Donor Type Antigen Antibody Clump?

A A Anti-A YES

O None Anti-A NO

Why are Type O people called universal donors?

What would happen if you gave a type O person, type B blood?

Who is the universal recipient?

Blood Splatter AnalysisBlood Splatter Analysis

• The location, distribution, and appearance of bloodstains and spatters may be useful for interpreting and reconstructing the events that may have occurred in a crime.

• A thorough analysis of the position and shape of blood patterns with respect to their origin and trajectory must be determined.

www.rfview.net/ModsPage1.htm

Stain Patterns of BloodStain Patterns of Blood

• The harder and less porous surface• The less spatter results.

• Direction of travel of blood striking an object.• Pointed end of a bloodstain always faces its direction of travel.

• Impact of angle• Look at degree of circular distortion of the stain. A drop of blood striking a surface at right angles gives rise to a nearly circular stain. As the angle decreases, the stain becomes elongated in shape.

• Stain convergence on a two-dimensional plane.• Can be established by drawing straight lines through the long axis of several individual bloodstains. The intersection or point of convergence of the lines represents the point from which the blood emanated.

Blood Splatter at Crime SceneBlood Splatter at Crime Scene

• Photos of splatter patterns are important

• Close-up photos of individual drops can reveal critical information

• There may be more than one general pattern.

• Shape and size of drops should be recorded with micro scale visible in photo.

• Blood itself needs to be collected.

Velocity of SplatterVelocity of Splatter

• Pattern should reveal the velocity of the droplets.• The smaller the drops the faster they were moving.

• A fog of tiny droplets indicates high velocity most certainly a gunshot or an explosive device.

Many types of blood splatterMany types of blood splatter• In the field there may be several wounds, all with their own pattern.

• Impact splatters• Traveling drip patterns

• Result from blood that falls from a wounded person or person that has blood on them

• Bizarre splatter patterns• Droplets flicked from blood soaked hair of a running person.

• Weapons carried through scene especially blunt force weapons and knives can leave their own drip pattern.

• Arterial spurting• Patterns reflects the beating of a heart.

Serology LabSerology Lab

• In this lab you will be using simulated blood to determine blood types

• You will first use known blood types and look at the effects when adding antibody A or antibody B.

• You will then have unknowns to determine what blood type it is.

• Record all your work on the data sheets.• Make sure you answer all questions, and clean up when done.

BibliographyBibliography

• Genge, N. E., “The Forensic Casebook”, Ballantine Books, 2002

• Lee, Henry, “Crime Scene Handbook”. Academic Press, 2001.

• Saferstein, Richard, “Criminalistics an Introduction to Forensics Science”, Prentice Hall, 2001.

• Google Image Search, Blood typing and splatter analysis.