Forensic Serology Chapter 11 Forensic Science Amy Urling

Forensic Serology Serology: study of bodily fluids

Blood Plasma: liquid portion of blood; 55% of volume; includes dissolved proteins, carbohydrates, fats, salts, minerals, antibodies Red blood cells (erythrocytes): formed in bone marrow, responsible for transport of oxygen and carbon dioxide, have no nucleus White blood cells (leukocytes): formed in lymph nodes, protect our bodies against invading pathogens Platelets: part of blood clotting process

Label red blood cells, white blood cells, plasma Where is the DNA?

Is this human blood?

Locating Blood Luminol: undergoes chemiluminescence; causes blood or blood residue to appear blue to yellow-green in the dark Fluorescein: emits light in contact with blood, can be sprayed on vertical surfaces Phenolphthalien: turns pink in the presence of a base (or blood) Teichmann and Takayama Tests: confirm the presence of blood by turning it into crystals

ABO Blood Types A B AB O Blood Type Antigens Antibodies % of Pop. Can Receive Can Donate To A B AB O

Rh Factor + has Rh antigen - doesn’t have Rh antigen and has Rh antibodies

Questions Answered by Blood Spatter Interpretation Chapter 10 Questions Answered by Blood Spatter Interpretation The distance between the target surface and the origin of the blood 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 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 Kendall/HUnt

Blood Spatter: Conditions Affecting Shape of Blood Droplet Chapter 10 Blood Spatter: Conditions Affecting Shape of Blood Droplet Size of the droplet Angle of impact Velocity at which the blood droplet left its origin Height 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

Bloodstain Terminology Chapter 10 Bloodstain Terminology Angle of impact—angle at which blood strikes a target surface Bloodstain transfer—when a bloody object comes into contact with a surface and leaves a patterned blood image on the surface Backspatter—blood that is directed back toward the source of energy Cast-off—blood that is thrown from an object in motion Kendall/HUnt

Bloodstain Terminology, continued Chapter 10 Bloodstain Terminology, continued Contact stain—bloodstains caused by contact between a wet blood- bearing surface and a second surface that 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 that 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

Bloodstain Terminology, continued Chapter 10 Bloodstain Terminology, continued Directionality—relates to the direction a drop of blood travels in space from its point of origin 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 25 feet per second, usually 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 Kendall/HUnt

Impact The shape of a blood drop: Chapter 10 Impact 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; the angle can be determined by the following formula: The more acute the angle of impact, the more elongated the stain (and easier it is to determine direction of travel) 90-degree angles are perfectly round drops; 80-degree angles take on a more elliptical shape. At about 30 degrees the stain will begin to produce a tail. Kendall/HUnt

Chapter 10 Bloodstain Patterns The harder and less porous the surface, the less the blood drop will break apart. The softer and more porous the surface, the more the blood drop will break apart. The pointed end of the bloodstain faces the direction of travel. Kendall/HUnt

Area of Intersection and Convergence Chapter 10 Area of Intersection and Convergence The location of the blood source can be determined by drawing lines from the various blood droplets to the point where they intersect. The area of convergence is the point of origin—the spot where the “blow” occurred. It may be established at the scene by measurement of angles with the use of strings. Kendall/HUnt