FORENSIC SEROLOGY

FORENSIC SEROLOGY

Blood • A complex mixture of cells, enzymes, proteins & inorganic substances • Plasma - the liquid portion of the blood • Cellular portion of blood contains • red cells (erythrocytes, RBCs) – carry O2 • white cells (leukocytes, WBCs) – fight infection • Platelets (thrombocytes) – used for clotting

Blood Properties • Blood: • Accounts for about 8 % of total body weight. • 5 to 6 liters of blood for males. • 4 to 5 liters of blood for females. • A 40 percent blood volume loss, internally or/and externally, is required to produce irreversible shock (death)

Erythrocytes: Red Blood Cells (RBC) • Most abundant cells in the blood. Account for 40 to 45% of blood • Give blood its characteristic red color. • The ratio in normal blood is: 600 RBC:1 white blood cell :40 platelets. • Possess chemical structures on their surfaces called antigens or agglutinogens • Impart blood type characteristics • What makes RBCs unusual: • Have a strange shape • Have no nucleus. • Can change shape without breaking as they squeeze single file through the capillaries. • Contains hemoglobin

White Blood Cells (WBC) • Part of the immune system • Fight infection. • Circulate in the blood to be transported to an infection site. • In a normal adult body there are 4,000 to 10,000 WBCs per microliter of blood. Platelets • The clotting factors that are carried in the plasma • Clot together in a process called coagulation to seal a wound and prevent loss of blood.

Plasma • Clear, yellowish fluid • Sometimes appears milky after a fatty meal or when people have a high level of lipids in their blood. • Contains electrolytes, nutrients and vitamins, hormones, clotting factors, and proteins such as antibodies to fight infection. • Plasma is 90% water and 10% protein.

What is Serology? • The study of the proteins found in blood • Forensics focus on the antigen / antibody connection to determine blood typing

Forensic Blood Analysis • Identification (Is it blood?) • Blood origin (Is it human or other source?) • Blood Type

Identification (Is it blood?) • Hemoglobin has peroxidase-like activity (enzymes that accelerate oxidation of organic compounds). • Kastle-Meyer Test - uses phenolphthalein (an acid/base indicator) • Blood + phenolphthalein + peroxide (H2O2) → deep pink color • Can give false positives (horseradish, some vegetables, potatoes)

Luminol Test Reaction with blood produces a complex which can be seen by luminescence (“glow in the dark”) • Very sensitive • Detects unseen samples and patterns. • Does not interfere with later DNA testing.

Blood origin (Is it human or other source?) • Precipitin Test • Animals are injected with human blood to form antibodies • Isolate human antiserum • Human antiserum will react with human blood. • Antiserum can be made similarly for many other animals • Works on small, old, dried samples of blood

Blood Types • Karl Landsteiner (1900) • Noted that when blood from different people mixed it sometimes formed a precipitate - deadly if mixed in body. • Explored why? Blundell's blood transfusion apparatus, 19th century

Genetics of Blood Types • Your blood type is established before you are BORN, by specific GENES inherited from your parents. • You inherit one gene from your MOTHER and one from your FATHER. • These genes determine your blood type by causing proteins to exist on the surface of all of your red blood cells.

What are blood types? (ABO system) There are 3 common alleles or genes for blood type: A, B, & O. Since we have 2 genes, there are 6 possible combinations (genotypes) Blood Types AA or AO = Type ABB or BO = Type BOO = Type OAB = Type AB http://learn.genetics.utah.edu/units/basics/blood/types.cfm

Antibodies • Proteins that are present in plasma serum • Responsible for ensuring that the only blood cells that can survive in a person are cells of the correct blood type • Antibodies produced by the A alleles remove cells containing B antigens by clumping them together • Antibodies produced by the B alleles remove cells possessing A antigens Immunoassay: A technique utilizing antibodies to bind specifically to targeted substances in order to identify their presence

Type O Blood • Genotype is OO • Both parents passed on the O gene • have no antigens • can be introduced into a person with Type A or Type B because the cells are not attacked by antibodies • Have both A & B antibodies • can only have other O type cells mixed with this blood

Type A • Possessed by people with genotype • AA • AO • A is dominant to O • Contain B antibody

Type B • Possessed by people with genotype • BB • BO • B is dominant to O • Possess A antibody

Type AB • Possessed by people with genotype • AB • A & B are co-dominant • Contain no antibodies • can have A, B, AB, or O cells added

Rh Factors • While studying Rhesusmonkeys, 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. • The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor. • If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-). A+ A-B+ B-AB+ AB-O+ O-

How common is your blood type? 46.1% 38.8% 11.1% 3.9%

Blood Transfusions O A B AB • A procedure in which blood is given to a patient through an intravenous (IV) line in one of the blood vessels. • Done to replace blood lost during surgery or a serious injury. • May also be done if a person’s body can't make blood properly due to an illness. Universal Donor Universal Recipient

Who can give blood? Type O-is called the universal donor it can be given to anybody it has no protein to cause agglutination (clumps) Type AB+is the universal receiver because the recipient has all of the proteins and so will not form clumps (coagulation). Rh + : can receive + or - Rh- : can only receive -

Blood Spatter Analysis • The examination of the shapes, locations, and distribution patterns of bloodstains • Provides an interpretation of the physical events which gave rise to the origin. • Confirm or refute assumptions concerning events Position of victim (standing, sitting, lying). Evidence of a struggle. (blood smears, blood trails) • Confirm or refute statements made by people involved in the case: Are stain patterns on a suspects clothing consistent with his reported actions? Are stain patterns on a victim or at a scene consistent with accounts given by witnesses or the suspect?

Bloodstain Evidence • Direction from which blood originated • Angle of impact • Location or position of a victim when wound was inflicted • Movement of a bleeding individual • Number of blows that struck a bleeding victim • Approximate location of an individual delivering blows

Bloodstains – 3 patterns Projected Passive Transfer

Passive Bloodstains • Drops created or formed solely by the force of gravity. • Can be subdivided: • Drops • Drip patterns • Pools • Clots

Surface Bloodstains (Passive) • Type of surface the blood strikes affects the spatter pattern. • Blood droplets that strike a hard smooth surface will have little distortion around the edges • Blood droplets that strike linoleum flooring will often show small distortion around the edges • Blood droplets striking wood, carpeting or concrete are distorted to a larger extent (ex. spines, satellites spatter) Smooth Linoleum Concrete

. . . . . . Effect of Target Surface Spreads out smoothly ST of spreading edge is broken by irregular surface

Transfer Bloodstains • Created when a wet, bloody surface comes in contact with another surface • A recognizable image of the original surface may be observed (such as a hand or shoe pattern) • Subdivided: • Contact bleeding • Swipe or Smear • Wipe • Smudge.

Projected Bloodstains • Created when a blood source is subjected to an action greater than the force of gravity • The size, shape, and number of resulting stains will depend on the amount of force utilized to strike the blood source

Types of Projected Bloodstains • Arterial Spurt / Gush - blood spurt under pressure from a cut artery • Cast-off Stains - blood released or thrown from a blood-soaked object in motion • Impact Spatter - created when a blow or force results in the random dispersion of smaller drops of blood Arterial Cast-Off

Projected Bloodstains - Impact • Low Velocity - Gravitational pull.Relatively large stains4 mm and greater. • Medium Velocity- Stain size1 to 4 mm. • High Velocity- Stain size1 mm and smaller (Mist like appearance). Low Medium High

Tail of elongated stain points in direction of travel . Tail of wave cast-off points back to parent drop Parent drop wave cast-off Wave Cast-off

DIRECTIONALITY OF BLOODSTAINS • When a droplet of blood strikes a surface perpendicular (90 degrees) the resulting bloodstain will be circular. • Blood that strikes a surface at an angle less than 90 degrees will be elongated or have a tear drop shape. • Directionality is usually obvious as the tail will always point in the direction of travel.

IMPACT ANGLE DETERMINATION • ANGLE of IMPACT (AOI) is the acute angle formed between the direction of the blood drop and the plane of the surface it strikes By utilizing trigonometric functions its possible to determine the impact angle for any given blood droplet. SIN θ = opposite = _width___ hypotenuse length

Blood Spatter • SIN Ө= Width (a) = 1.5 cm Length (c) 3.0 cm

Area of Convergence 2 Dimensional Analysis – taken from multiple blood droplets

Area of Origin determination • 3 Dimensional Analysis • String method • Find the area of convergence • Calculate the angle of impact for each drop • Attach one end of a string to the end of a droplet • Using a protractor, lift the string until it matches the impact angle. Secure this end of the string • View the area of origin where strings appear to meet

Area of Origin determination Law of Tangents • Determine the direction of blood flow • Use line of convergence to determine the position of the victim • Calculate the angle of impact for individual drops of blood spatter • Determine the distance from the blood droplet to the area of convergence (this is the adjacent) • Use tangent formula to determine area of origin (height) tan55° = opposite = height__ adjacent 57 height = (57)(tan55°) = 81.4"

FORENSIC SEROLOGY