Forensic Science: Fundamentals & Investigations, Chapter 8 1 Chapter 8 Blood and Blood Splatter By the end of this chapter you will be able to: o Explain the composition of blood o Describe the function of blood cells o Determine the blood type of a blood sample o Conduct a blood splatter analysis o Examine wounds and describe the nature of the weapon o Find and process blood evidence All Rights Reserved South-Western / Cengage Learning © 2012, 2009

Forensic Science: Fundamentals & Investigations, Chapter 8 2 Introduction and History o Blood typing provides class evidence o DNA profiling provides individual evidence o A blood splatter pattern provides information the truthfulness of an account by a witness or a suspect the origin of the blood the angle and velocity of impact the type of weapon used

Forensic Science: Fundamentals & Investigations, Chapter 8 3 Composition of Blood o Plasma—a liquid suspending other blood components o Red blood cells (Erthrocytes)—carries oxygen to the body’s cells and carbon dioxide away o White blood cells (Leukocytes)—fights disease and foreign invaders and, alone, contain cell nuclei o Platelets—aids in blood clotting and the repair of damaged blood vessels

Forensic Science: Fundamentals & Investigations, Chapter 8 4 Composition of Blood

Forensic Science: Fundamentals & Investigations, Chapter 8 5 Types of Blood Cells

Forensic Science: Fundamentals & Investigations, Chapter 8 6 Cellular Components of Blood

Forensic Science: Fundamentals & Investigations, Chapter 8 7 Blood Typing—Proteins o Discovered in 1900 by Karl Landsteiner o Identifies the presence or absence of particular proteins embedded in the cell o Quicker and less expensive than DNA profiling o Produces class evidence but can still link a suspect to a crime scene or exclude a suspect

Forensic Science: Fundamentals & Investigations, Chapter 8 8 Blood Typing—Proteins 42%12%3%43% of the population in the United States

Kendall/Hunt Publishing Company 9 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

Forensic Science: Fundamentals & Investigations, Chapter 8 10 Rh Factor 85% of the population has a protein called RH factor on their blood cells

Forensic Science: Fundamentals & Investigations, Chapter 8 11 Blood Typing—Antibodies o Antibodies are Y-shaped proteins secreted by white blood cells that attach to antigens to destroy them o Antigens are foreign molecules or cells that react to antibodies

Forensic Science: Fundamentals & Investigations, Chapter 8 12 Blood Enzymes o Enzymes are complex proteins that catalyze different biochemical reactions o Many enzymes and proteins have been found in the blood that are important for identification purposes

Kendall/Hunt Publishing Company 13 Unknown Stain at a Scene Questions to be answered: o Is it blood? o Is it human blood? o Whose is it? Determine blood type, alcohol content, drugs present Determine the method(s) in which blood may have been deposited

Presumptive Tests for Blood Determination

Kendall/Hunt Publishing Company 15 Kastle-Meyer color test o A mixture of phenolphthalein and hydrogen peroxide o The hemoglobin will cause the formation of a deep pink color if blood is present o Not specific for blood—can turn pink in presence of some veggies such as potatoes or horseradish

Hematest® tablet o Reacts with the heme group in blood causing a blue-green color o Originally designed as a urine dipstick test for blood Kendall/Hunt Publishing Company 16

Luminol test o Reaction with blood to produce light (luminescence) o Can be sprayed onto large areas o Very sensitive—can detect blood diluted up to 300,000 times (trace patterns) o Does not degrade DNA Kendall/Hunt Publishing Company 17

Kendall/Hunt Publishing Company 18 Human vs Animal Blood o Microscopic observation

Kendall/Hunt Publishing Company 19 Animal Blood Larger nucleic red blood cells Frog Blood

Kendall/Hunt Publishing Company 20 Human Blood o Red blood cells are most numerous; 5 to 6 million per mm 3 o White blood cells are larger and less numerous; 5 to 10,000 per mm 3 o Platelets are tiny, cellular fragments; 350 to 500,000 per mm 3

Forensic Science: Fundamentals & Investigations, Chapter 8 21 Blood Spatter o 1939—spatter patterns first analyzed o Blood may spatter when a wound is inflicted o Blood spatter pattern—a grouping of blood stains o Patterns help to reconstruct the events surrounding a shooting, stabbing, or beating

Forensic Science: Fundamentals & Investigations, Chapter 8 22 Blood Spatter Analysis Analysis of a spatter pattern can aid in determining the: direction blood traveled angle of impact point of origin of the blood velocity of the blood manner of death

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Kendall/Hunt Publishing Company 24 Blood Pattern Reconstruction Scene Pattern Reconstruction 1. Stain condition 2. Pattern 3. Distribution 4. Location 5. Directionality Lab Results Reconstruction 1. Genetic marker typing 2. Age Determination 3. Source Determination 4. Race Determination 5. Sex Determination —From “Cracking Cases” by Dr. Henry C. Lee

Kendall/Hunt Publishing Company 25 Blood Droplet Characteristics o A blood droplet will remain spherical in space until it collides with a surface o Once a blood droplet impacts a surface, a bloodstain is formed.

Characteristics cont. o A droplet falling from the same height, hitting the same surface at the same angle, will produce a stain with the same basic shape. Kendall/Hunt Publishing Company 26

Kendall/Hunt Publishing Company 27 Conditions Affecting Shape of Blood Droplet o Size of the droplet o Angle of impact o Velocity at which the blood droplet left its origin

Conditions cont. o Height o 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 Kendall/Hunt Publishing Company 28

Kendall/Hunt Publishing Company 29 Bloodstain Terminology o Angle of impact—angle at which blood strikes a target surface. o Bloodstain transfer—when a bloody object comes into contact with a surface and leaves a patterned blood image on the surface

Bloodstain Terminology o Backspatter—blood that is directed back toward the source of energy o Cast-off—blood that is thrown from an object in motion Kendall/Hunt Publishing Company 30

Kendall/Hunt Publishing Company 31 Bloodstain Terminology o Contact stain—bloodstains caused by contact between a wet blood-bearing surface and a second surface which may or may not have blood on it  Transfer—an image is recognizable and may be identifiable with a particular object  Swipe—wet blood is transferred to a surface which did not have blood on it  Wipe—a non-blood bearing object moves through a wet bloodstain, altering the appearance of the original stain

Kendall/Hunt Publishing Company 32 Bloodstain Terminology o Directionality—relates to the direction a drop of blood traveled in space from its point of origin o Terminal velocity—the greatest speed to which a free falling drop of blood can accelerate in air. Dependent upon the acceleration of gravity and the friction of the air against the blood— approximately 25.1 feet/second.

High Velocity Blood Spatter Greater than 25 feet per second, usually 100 feet per second Gives a fine mist appearance Kendall/Hunt Publishing Company 33

Medium Velocity Blood Spatter 5 to 25 feet per second Kendall/Hunt Publishing Company 34

Low Velocity Blood Spatter 5 feet per second or less Kendall/Hunt Publishing Company 35

Bloodstain Patterns The shape of a blood drop: Round—if it falls straight down at a 90 degree angle. Elliptical—blood droplets elongate as the angle decreases from 90 to 0 degrees Kendall/Hunt Publishing Company 36

Forensic Science: Fundamentals & Investigations, Chapter 8 37 Natural cohesiveness of blood

Kendall/Hunt Publishing Company 38 Impact o The more acute the angle of impact, the more elongated the stain. o 90 degree angles are perfectly round drops 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. Kendall/Hunt Publishing Company 39

Kendall/Hunt Publishing Company 40 Bloodstain Patterns o The harder and less porous the surface, the less the blood drop will break apart. o The softer and more porous the surface, the more a blood drop will break apart. o The pointed end of the blood stain faces the direction of travel.

Forensic Science: Fundamentals & Investigations, Chapter 8 41 Blood Splatter Analysis o Satellite droplets— When blood falls from a height, or at a high velocity, It overcomes its natural cohesiveness, and Separates from the main droplet o Spiking patterns— Form around the droplet edges when blood falls onto a less-than-smooth surface

Forensic Science: Fundamentals & Investigations, Chapter 8 42 Blood Splatter Analysis —Directionality The shape of an individual drop of blood provides clues to the direction from where the blood originated. How will the point of impact compare with the rest of a blood pattern?

Forensic Science: Fundamentals & Investigations, Chapter 8 43 Blood Spatter Analysis Lines of convergence—two or blood spatters can pinpoint the location of the blood source

Forensic Science: Fundamentals & Investigations, Chapter 8 44 Blood Splatter Analysis —Six Patterns Describe each of these: a) Passive drops b) Arterial gushes c) Splashes d) Smears e) Trails f) Pools

Forensic Science: Fundamentals & Investigations, Chapter 8 45 Blood Splatter Analysis —Impact Patterns can help investigators determine the type of weapon used o What kind of a pattern is produced by a gun shot? o What kind of a pattern is produced by a hammer blow?

Forensic Science: Fundamentals & Investigations, Chapter Summary o Blood consists of cellular components and plasma. o The various human blood types are caused by the presence or absence of A and/or B proteins on the surface of red blood cells. o Blood splatter evidence can be used to recreate a crime scene. o Investigators endeavor to (a) locate, (b) identify, and (c) interpret blood splatter patterns at crime scenes.