BLOOD

What is blood made of? Plasma-- fluid portion of the blood including clotting factors (fibrinogen) (55%) Cells (45%) –Erythrocytes-- red blood cells; responsible for oxygen distribution –Leukocytes-- white blood cells; responsible for “cleaning” the system of foreign invaders –Thrombocytes-- platelets; responsible for blood clotting Serum-- liquid that separates from the blood when a clot is formed (excluding clotting factor fibrinogen)

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Until recently … ABO blood groups-- based on having an A, B, both or none of the factors on the red blood cell Rh factor-- may be present on the red blood cell; positive if present and negative if not Antigen-- a substance found on a red blood cell –A or B antigens, Rh antigen Antibody-- a substance that reacts with an antigen Agglutination-- clumping of red blood cells; will result if blood types with different antigens are mixed

Blood Genetic Terminology Genotype--letters that represent the traits; ie, AA, AO, BO, BB, AB and OO Phenotype--words that describe the traits Heterozygous--different alleles for the same trait; ie: AO, BO, AB Homozygous--the same alleles for the trait; ie: AA, BB, OO **Before DNA, blood groups were the main ways to identify blood. It could not be INDIVIDUALIZED!

Blood Questions to be answered at a crime scene: Where is it? Is it blood? Is it human blood? Whose is it? –Determine blood type, alcohol content, drugs present How did it get there? –Determine the method(s) in which blood may have been deposited

Presumptive Tests for Blood IS IT BLOOD? Kastle-Meyer color test-- phenolophthalein and hydrogen peroxide are mixed together the blood’s hemoglobin will cause the formation of a deep pink color

Leucomalachite test--leucomalachite green mixed with acetic acid and distilled water; then a drop of sodium perborate will turn blood green and then darken. 10

Luminol test--reaction with blood results in the production of light 11

Other Tests for Blood Microcrystalline tests--add specific chemicals to the blood in order to form characteristic crystals –Takayama –Teichmann **These tests are very sensitive to contaminants.

Presumptive Tests

Human vs Animal Microscopic survey Precipitin test - human blood is injected into a rabbit; antibodies are formed; rabbit’s blood is extracted as an antiserum; the antiserum is placed on sample blood. It will react with human proteins. (A precipitin band forms.) This test is very sensitive and requires only a small amount of blood.

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Animal Blood Animal blood has different microscopic characteristics than human blood. Ex)Frog Blood Larger nucleic red blood cells

Human Blood Numerous non-nucleic red blood cells--5 to 6 million per µL Larger but less numerous white blood cells 5 to 10,000 per µL Tiny, cellular fragments 350 to 500,000 per µL called platelets

Historical Perspective Of Blood Typing Around 1900, Karl Landsteiner discovered that there are four different kinds of human blood based on the presence or absence of specific antigens found on the surface of the red blood cells. In 1940 Landsteiner and Weiner reported the discovery of the Rh factor by studying the blood of the Rhesus monkey. 85% of Caucasians, 94% of Black Americans and 99% of all Asians are Rh positive.

Blood Typing No longer significant … why??? A blood type has antigen A and will agglutinate with B. B blood type has antigen B and will agglutinate with A. AB blood type has antigen A and B and will not agglutinate with either A or B. O blood type has neither antigen A or B and will agglutinate with either.

Blood Groups Type Antigen Antibody Can Give Blood To: Can Get Blood From A B AB O A B A and B Neither A nor B B A Neither A nor B A and B A, ABO, A B, ABO, B AB A, B, O, AB O

Blood Reactions to Antiserum REACTION BLOOD TYPE Anti-A SerumAnti-B Serum Agglutination No agglutination Agglutination No agglutination Agglutination No agglutination Type A Type B Type AB Type O

Population Distribution of Blood Types in the U. S. 22 CaucasiansAfrican AmericanHispanicAsian O +37%47%53%39% O -8%4% 1% A +33%24%29%27% A -7%2% 0.5% B +9%18%9%25% B -2%1% 0.4% AB + 3%4%2%7% AB -1%0.3%0.2%0.1%

23 BLOOD PATTERNS: Reconstructing the Event SCENE PATTERN RECONSTRUCTION What do we look at? 1. Stain condition 2. Pattern 3. Distribution 4. Location 5. Directionality

24 Blood Stain Spatter A field of forensic study which deals with the physical properties of blood and the patterns produced under different conditions as a result of various forces being applied to the blood.

Blood, as a fluid, follows the laws of physics. It is not influenced nor affected by race, gender, or age of the one bleeding. 25

26 BLOOD DROPLET Characteristics A blood droplet will remain spherical in space until it drops onto a surface. It doesn’t look like the picture! Once a blood droplet impacts a surface, a bloodstain is formed. A droplet falling from the same height, hitting the same surface at the same angle, will produce a stain with the same basic shape. NO!

27 BLOOD DROPLET Volume Is approximately 0.05 mL Is not the same for all blood droplets--from 0.03 mL to 0.15 mL Is dependent upon the surface or orifice from which it originates The impact area is called the target.

28 CONDITIONS AFFECTING BLOODSTAIN SHAPE Size of the droplet Angle of impact Velocity at which the blood droplet left the original surface Texture of the target surface –On clean glass or plastic--droplet will have smooth outside edges –On a rough surface--will produce scalloping on the edges (SPINES).

29 Questions Answered by Blood Spatter Interpretation The distance between the target surface and the origin of blood at the time of blood shed The point(s) of origin of the blood Movement and direction of a person or an object The number of blows, shots, etc. causing the bloodshed and/or the dispersal of blood.

30 Questions Answered by Blood Spatter Interpretation Type and direction of impact that produced the bloodshed The position of the victim and/or object during bloodshed Movement of the victim and/or object after bloodshed

How distance affects blood spatter size

The further away the point of origin is from the target surface, the larger the blood droplet pattern will be. 32

Single vs. Multiple Drips SATELLITE SPATTER

34 Blood Stains The harder, smoother, and less porous the surface, the less the blood drop will break apart. The softer, rougher, and more porous the surface, the more a blood drop will break apart.

Directionality of Bloodstains Directionality--relates to the direction a drop of blood traveled in space from its point of origin The pointed end of the blood stain faces the direction the stain is traveling. 35

Walking Drip Pattern

37 Bloodstain Terminology Backspatter-- blood that is directed back toward its source of energy. Cast-off-- blood that is thrown from an object in motion

Backspatter and Castoff

39 Bloodstain Terminology Contact stain-- general term referring to bloodstains caused by contact between a wet, blood-bearing surface and a second surface which may or may not have blood on it –Transfer - When a bloody object comes into contact with a surface and leaves a patterned blood image on the surface. The image is recognizable and may be identifiable with a particular object –Swipe - When wet blood is transferred to a surface which did not first have blood on it –Wipe – When a non-blood bearing object moves through a wet bloodstain, altering the appearance of the original stain

Transfers, Swipes, Wipes Transfer Swipe Wipe

41 Bloodstain Terminology Terminal velocity-- the greatest speed to which a free falling drop of blood can accelerate in air. It is dependent upon the acceleration of gravity and the friction of the air against the blood--approximately 25:1 feet/second. –High velocity-- greater than 100 feet per second; gives a fine mist appearance –Medium velocity-- 5 to 25 feet per second. –Low velocity--5 feet per second or less

Low Velocity 5 feet per second or less

Medium Velocity Spatter 5 to 25 feet per second.

High Velocity Spatter greater than 100 feet per second; gives a fine mist appearance

45 Bloodstain Pattern Angle of Impact – the acute angle formed between the direction of a blood drop and the plan of the surface it strikes.

46 Angle of Impact Angle of impact--angle at which blood strikes a target surface. The shape of a blood stain: l Round--if it falls straight down at a 90 degree angle. l Elliptical--Blood droplet elongates as the angle decreases from 90 to 0 degrees. The angle can be determined by the following formula: Sin -1 width = angle of impact length

47 ANGLE OF IMPACT The more acute the angle of impact, the more elongated the stain. 90 degree angles are perfectly round with 80 degree angles taking on a more elliptical shape. At about 30 degrees the stain will begin to produce a tail. The more acute the angle, the easier it is to determine the direction of travel.

Angles of Impact Small Angle of Impact Large

49 Area of Convergence (intersection) Area of convergence is the common area of intersection on a 2D surface. The location of the blood source can be determined by drawing lines the various blood droplets to the point where they intersect. This is the blood’s origin.

50 Area of Origin The area of convergence is the point of origin in a 3D space; the spot where the “blow” occurred. It is determined by drawing a line from the area of convergence straight up to where to where the angle of impact would intersect

Area of Origin 51

Area of convergence vs. origin 52

Arterial Blood Spurts

54 Blood Evidence Class evidence for blood would include blood type. If you can determine the DNA you would have individual evidence. Blood stain patterns are considered circumstantial evidence in a court room. Experts could argue many points including direction of stains, height of the perpetrator, position of the victim, left/right hand, whether the body was moved, etc.

Other Physiological Fluids Semen –Many of the cases sent to a forensic laboratory involve sexual offenses, making it necessary to examine exhibits for the presence of seminal stains. Saliva Urine 55

56 Semen Determination of Seminal Fluid Visual Observation – may not be obvious Acid phosphatase color test –the presence of acid phosphatase, the enzyme secreted by the prostate gland into the seminal fluid, will turn purple for a positive test. – It will also fluoresce under UV light.

57 Sperm Among the smallest and most highly specialized cells in the human body. Has a head and a tail Contains 23 chromosomes with the genetic material found in the head There are approximately 100 million sperm per milliliter. Two conditions may not show sperm. (Oligospermia and Aspermia.) Magnified 400X

58 Semen (cont.) Determination of Seminal Fluid Prostate Specific Antigen (PSA) or p30--unique to seminal plasma –P30 is isolated and injected into a rabbit where antibodies are produced (anti-p30) –The stain extract is placed in one well of an electrophoresis plate and the anti-p30 in the opposite well. The electricity is applied and the antigens and antibodies move toward each other. The formation of a precipitation line between the wells shows the presence of p30 in the sample stain. It must be seminal fluid.

Collection of Rape Evidence The rape victim must undergo a medical examination as soon as possible after the assault. At that time the appropriate items of physical evidence including clothing, hairs, and vaginal and rectal swabs can be collected for subsequent laboratory examination. All outer and undergarments should be carefully removed and packaged separately in paper (not plastic) bags. Bedding, or the object upon which the assault took place, may also be carefully collected. 59

Collection of Rape Evidence If a suspect is apprehended within 24 hours of the assault, it may be possible to detect the victim’s DNA on the male’s underwear or on a penile swab of the suspect. Items routinely collected from the suspect include all clothing, pubic hair, head hair, penile swab, and a blood sample or buccal swab for DNA typing. The forceful physical contact between victim and assailant may result in a transfer of such physical evidence of blood, semen, saliva, hairs, and fibers. 60

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