BloodTyping & Spatter

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Forensic serology is the detection, classification and study of various bodily fluids such as blood, semen, fecal matter and perspiration, and

their relationship to a crime scene.

A forensic serologist may also be involved in DNA analysis and bloodstain pattern analysis.

• Blood is the bodies main transport system of oxygen and nutrients.

• Blood carries waste to the lungs, liver, kidney for disposal.

• Fights against infections and heals wounds.

• We roughly have 5 liters of blood (7-8% of body weight).

What is Blood?

What Makes up our Blood?

• RED BLOOD CELLS (Erythrocytes) – The mostabundant cells in our blood; they are produced in the bonemarrow and contain a protein called hemoglobin thatcarries oxygen to our cells.

• WHITE BLOOD CELLS (Leukocytes) – They are partof the immune system and destroy infectious agentscalled pathogens.

• PLASMA – This is the yellowish liquid portion of bloodthat contains electrolytes, nutrients and vitamins,hormones, clotting factors, and proteins such asantibodies to fight infection.

• PLATELETS (Thrombocytes) – The clotting factors thatare carried in the plasma; they clot together in a processcalled coagulation to seal a wound and prevent a loss ofblood.

History of Blood Serology

Early accounts of blood transfusions performed in 1818

1901 Karl Landsteiner –Blood Types

1930 Nobel Prize

1937 Rh Factor

1990 Use of blood factors (ABO & MN) linking blood to individual

DNA in blood is used to individualize blood evidence

Antigens• On the surface of each RBC, chemical

structures called antigens, are found

• The most important antigen systems are the A-B-O and Rh systems

• If a person has A blood, then they have A antigens

• B blood has B antigens

• AB blood has both A and B antigens

• O has no antigens

• The presence of A and B antigens determines a person’s blood type

D Antigen (Rh factor)

• While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein.

• If a person has the D antigen, they are Rh positive

• If they lack it, then they are Rh negative

• The presence or absence of three antigens-A, B, and D- must be determined in testing compatibility of the donor and recipient

Antibodies• Serum contains proteins called antibodies,

which destroy a specific antigen

• An antibody reacts only with its specific antigen and no other

• Type A blood has A antigens, anti-B antibodies

• Type B blood has B antigens, anti-A antibodies

• Type AB has A and B antigens, no antibodies

• Type O blood has no antigens, anti-A and anti-B antibodies

What are blood types?

http://learn.genetics.utah.edu/units/basics/blood/types.cfm

There are 3 alleles or genes for blood type: A, B, & O.

Since we have 2 genes, there are 6 possible

combinations.

Blood Types

AA or AO = Type A

BB or BO = Type B

OO = Type O

AB = Type AB

Heredity

Heredity

• All antigens are genetically determined traits

• Inherited from parents and are part of the biological makeup once that person has been conceived

• Genetic material is transferred by genes

• Genes are located on chromosomes that are located inside the nucleus

• Almost all human cells have 46 chromosomes

• The only exceptions are the gametes, which are sperm and egg cells, which contain 23 chromosomes

Sex Cells

• Females carry X chromosomes

• Males carry X and Y chromosomes

• When an X sperm fertilizes the female egg, it now contains XX, which is female

• When a Y sperm fertilizes the female egg, it now contains XY, which is male

• The sperm cell determines the chromosome pair, so males determine the sex of the child

Genotype and Phenotype

•A pair of genes makes up the genotype

•No known lab test can determine an individual’s A-B-O genotype

•A phenotype is a person’s outward characteristic, such as having A blood

• This still does not tell whether the genotype is AA or AO

• It can only be determined by studying the family history

Paternitytesting

• No blood can appear in a child unless it is present in at least one of the parents

• Has important implications in disputed paternity cases, which are encountered in civil, not criminal, cases

• Many cases can be solved by comparing the blood types of mother and suspected father

• If the father can not be excluded, then all that can be said is that he may be the father because of blood typing, but does not strictly mean he is the father

• Further testing, such as DNA, will be required

Common Blood Factors

What are blood types?

http://learn.genetics.utah.edu/units/basics/blood/types.cfm

There are 3 alleles or genes for blood type: A, B, & O.

Since we have 2 genes, there are 6 possible

combinations.

Blood Types

AA or AO = Type A

BB or BO = Type B

OO = Type O

AB = Type AB

ABO System

• In the ABO system there are two different blood proteins: Aand B

• The inheritance of these factors is based on codominance of the A and B proteins

• In codominance, both alleles (different forms of a gene) in the heterozygote express themselves fully

• There are 3 different blood alleles:• The A and B genes are both dominant

• The o gene is recessive

Abo system (cont.)

• Based on the 3 genes there are 4 possible phenotypes:• Type A blood

• Type B blood

• Type AB blood

• Type O blood

• There are 6 possible genotypes: AA, Ao, BB, Bo, AB, O

Possible Genotypes

AA Ao BB Bo AB oo

Blood Types

Type A Type A Type B Type B Type AB Type O

Abo system (cont.)

• The inheritance of the ABO system can be predicted using Punnett squares

• EX: A woman who is heterozygous for Type A blood has a child with a man who is heterozygous for Type B blood. What are the possible genotypes and phenotypes of their child?

A o

B

o

AB

ooAo

BoGenotypes: AB, Bo, Ao, oo

Phenotypes: Type AB, Type B,Type A, Type O

Abo system (cont.)

• This system is important not only in forensics but in the medical field

• It is important for blood transfusions

• It is essential that the ABO blood types match to prevent the blood from clumping

Mns system

•Similar to the ABO System

•A person carries either the M protein, the N protein or the S protein on their blood cells

•M is found in 30% of the population

•N is found in 22% of the population

•S is found in 48% of the population

Rh Factor

• The Rh protein can be found on the surface of the blood cell

• Rh+: the person has the Rh antigen; it is found in 84% of the population

• Rh-: the person does not have the Rh antigen; makes up 16% of the population

O+ 38 percent of population O- 7 percent of populationA+ 34 percent of population A- 6 percent of populationB+ 9 percent of population B- 2 percent of populationAB+ 3 percent of population AB- 1 percent of population

Blood Typing

What are blood types?

http://learn.genetics.utah.edu/units/basics/blood/types.cfm

There are 3 alleles or genes for blood type: A, B, & O.

Since we have 2 genes, there are 6 possible

combinations.

Blood Types

AA or AO = Type A

BB or BO = Type B

OO = Type O

AB = Type AB

How common is your blood type?

46.1%

38.8%

11.1%

3.9%

Blood TransfusionsA blood transfusion is a procedure in which blood is given to a patient through an

intravenous (IV) line in one of the blood vessels. Blood transfusions are done to replace

blood lost during surgery or a serious injury. A transfusion also may be done if a person’s

body can't make blood properly because of an illness.

Who can give you blood?

People with TYPE O blood are called Universal

Donors, because they can give blood to any

blood type.

People with TYPE AB blood are called

Universal Recipients, because they can receive

any blood type.

Rh + Can receive + or -

Rh - Can only receive –

Universal Donor

Universal Recipient

Calculating probabilities

•Knowing the percentages of the population with the different blood factors can be used to determine the likelihood of a certain combination of blood factors

•By multiplying the ratios of the types, you can determine the probability of having a certain blood type

Calculating probabilities (cont.)•EX: What is the probability of a person having blood

type A and N and being Rh-?

A N Rh-

40% x 22% x 16% = ?

.40 x .22 x .16 = .01

• 1 out of every 100 people would have blood type A and N and be Rh-

BloodTyping & Spatter

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Blood Forensics Serology and Spatter

If blood is suspected, a criminalist must answer the following questions:

1. Is it blood?2.From what species did the blood originate?

3.If the blood is human, how closely can it be associated with a specific person?

MicroscopicViews

Bird Blood

Cat Blood

Dog Blood

Fish Blood

Frog Blood

Snake BloodHuman Blood

Horse Blood

What does the abbreviation BPA represent? Bloodstain Pattern Analysis

What can an investigator learn from the analysis of a blood spatter?

Type and velocity of weapon

Number of blows

Handedness of assailant (right or left-handed)

Position and movements of the victim and assailant during and after the attack

Which wounds were inflicted first

Type of injuries

How long ago the crime was committed

Whether death was immediate or delayed

http://www.crimescenetwo.com/img/popup/book2p2.jpg

Light Source

Investigators will first examine the crime scene to look for areas that may

contain blood. They may use a high-intensity light or UV lights to help them

find traces of blood as well as other bodily fluids that are not visible under

normal lighting conditions.

How is blood evidence detected at a crime scene?

Blood Reagent Tests

These tests, referred to as presumptive tests, are used to detect blood at crime

scenes based upon the properties of hemoglobin in the blood. Further tests at the

crime lab can determine if it is human blood or not.

Examples:

Phenolphthalein is a chemical that is still utilized today and is usually referred

to as the Kastle-Meyer test and produces a pink color when it reacts with

hemoglobin.

HemaStix is a strip that has been coated with tetramethylbenzidine (TMB) and

will produce a green or blue-green color with the presence of hemoglobin.HemaStix

Kastle-Meyer

Luminol

This chemical is used by crime scene investigators to locate traces of blood, even if it has been

cleaned or removed.

Investigators spray a luminol solution is throughout the area under investigation and look for

reactions with the iron present in blood, which causes a blue luminescence.

One problem is that other substances also react, such as some metals, paints, cleaning products, and

plant materials. Another problem is that the chemical reaction can destroy other evidence in the

crime scene.Luminol Reaction

LCV or Leuco Crystal Violet, is one type of chemical process that is used for blood enhancement.

Using this test helps to make the blood evidence more visible so it can be photographed and

analyzed.

Fluorescein

This chemical is also capable of detecting latent or old blood, similar to luminol. It is ideal for fine

stains or smears found throughout a crime scene. After the solution has been sprayed onto the

substance or area suspected to contain blood, a UV light and goggles are used to detect any

illuminated areas, which appear greenish-white if blood is present. It may also react to many of the

same things as luminol (copper and bleach).

Fluorescein Reaction in

UV Light

LCV

Bloodstain Pattern Analysis Terms

• Spatter – Bloodstains created from the application of force to the area where the blood originated.

• Origin/Source – The place from where the blood spatter came from or originated.

• Angle of Impact – The angle at which a blood droplet strikes a surface.

Parent Drop

Spines

Satellite Spatters• Parent Drop – The droplet from which a satellite spatter

originates.

• Satellite Spatters – Small drops of blood that break of

from the parent spatter when the blood droplet hits a

surface.

• Spines – The pointed edges of a stain that radiate out from

the spatter; can help determine the direction from which the

blood traveled.

• Passive Bloodstains

• Patterns created from the force of gravity

• Drop, series of drops, flow patterns, blood pools, etc.

• Projected Bloodstains

– Patterns that occur when a force is applied to the source of the blood

– Includes low (5 ft/s or less), medium (5-25 ft/s), or high (greater than 25 ft/sand gives a fine mist appearance) impact spatters, cast-off blood that isthrown from an object in motion, arterial spurting when blood exits thebody under pressure, expiratory blood blown out of the nose, mouth, orwound.

• Transfer or Contact Bloodstains

– These patterns are created when a wet, bloody object comes in contact withanother surface; may be used to identify an object or body part.

– A wipe pattern is created from an object moving through a bloodstain, aswipe pattern is created from an object leaving a bloodstain, .

Types of Bloodstain Patterns

• The location, distribution, and appearance of bloodstains and spatters are useful for interpreting and reconstructing events that produced the bleeding

• They need to trace the direction, dropping distance, and angle of impact of a stain

Bloodstain Patterns

• The harder and less porous the surface, the less spatter

• If it hits glass, which is nonporous, the stain should be circular without much splatter

• If it hits a cotton sheet, which is porous, more splatter will be seen

Surface Texture

• Interpretation of the direction can be seen by the stain’s shape

• The pointed end of a bloodstain always faces its direction of travel before striking the surface

Direction of Travel

• Its possible to determine the impact angle of blood on a flat surface by measuring the degree of circular distortion of the stain

• If blood strikes a surface at 90o, it produces a nearly circular stain

• As the angle decreases, the stain gets longer

• To determine the angle, use the formula:

Sin=width/length

Impact Angles

Trigonometry:

Calculating impact angles

• Drop patterns are created by droplets landing at different angles from the same height.

• In order to recreate a blood stain at different angles, place a piece of paper on the clip board and align the

clipboard with the required angle line using a protractor. Hold a bottle of blood at a desired height from

the top of a table.

• GENTLY squeeze the bottle so that ONE drop of blood is released and lands on the paper.

• Continue testing by dropping blood from at the same height being used at each of the other angles.

Compare the angles.

Recreating Angles of Impact

Angle

Guide

Clipboard & Paper

Height of

50 cm

• The origin can be established by drawing straight lines through the long axis of several individual blood stains

• By examining at least two drops of blood, you will be able to determine where the injured person was located when the injury occurred in 2-D

Origin of Blood Spatter