8-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein FORENSIC SEROLOGY Chapter 8

8-2 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Serology The term serology is used to describe a broad scope of laboratory tests that use specific antigen and serum antibody reactions. The identity of each of the four A-B-O blood groups can be established by testing the blood with anti-A and anti-B sera. The concept of specific antigen–antibody reactions has been applied to immunoassay techniques for the detection of drugs of abuse in blood and urine.

8-3 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Nature of Blood The word blood refers to a highly complex mixture of cells, enzymes, proteins, and inorganic substances. Antigens, usually proteins, are located on the surface of red blood cells and are responsible for blood-type characteristics.

8-4 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein What makes up our blood? RED BLOOD CELLS (erythrocytes) – The most abundant cells in our blood; they are produced in the bone marrow and contain a protein called hemoglobin that carries oxygen to our cells. WHITE BLOOD CELLS (leukocytes) – They are part of the immune system and destroy infectious agents called pathogens. PLASMA – The yellowish liquid portion of blood that contains electrolytes, nutrients and vitamins, hormones, clotting factors, and proteins such as antibodies to fight infection. PLATELETS (thrombocytes) – The clotting factors that are carried in the plasma; they clot together in a process called coagulation to seal a wound and prevent a loss of blood.

8-5 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Blood Typing More than 15 blood antigen systems have been identified, but the A-B-O and Rh systems are the most important. An individual that is type A has A antigens on his/her red blood cells, type B has B antigens, AB has both A and B antigens, and type O has neither A nor B antigens. For every antigen there is a specific antibody that will react with it to form clumps known as agglutination. Thus, if serum containing anti-B is added to red blood cells carrying B antigen, they will immediately react.

8-6 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein What are blood types? 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

8-7 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Rh Factors Scientists sometimes study Rhesus monkeys to learn more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. Rh factor is determined by the presence of another antigen, the D antigen. 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-

8-8 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein ABO and Rh Factors Blood Type & %Can Donate toCan Receive from A+ 34% A- 6% B+ 9% B- 2% AB+ 3% AB- 1% O+ 37% O- 8%

8-9 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Immunoassay A number of immunological assay techniques are commercially available for detecting drugs through antigen-antibody reaction. One such technique, the enzyme-multiplied immunoassay technique (EMIT), is used by toxicologists because of its speed and high sensitivity for detecting drugs in urine. In a typical EMIT analysis, antibodies that will bind to a specific drug are added to the subject’s urine. Other immunoassay procedures are also available, such as radioimmunoassay (RIA), which uses drugs labeled with radioactive tags.

8-10 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein In the EMIT assay, a drug that may be present in a urine specimen will compete with added labeled drug for a limited number of antibody binding sites. The labeled drugs are indicated by an asterisk. Once the competition for antibody sites is completed, the number of remaining unbound labeled drug is proportional to the drug’s concentration in urine.

8-11 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Antigen-Antibody Reaction When an animal, such as a rabbit or mouse, is injected with an antigen its body will produce a series of different antibodies, all of which are designed to attack some particular site on the antigen of interest. This collection of antibodies is known as polyclonal antibodies ~ less specific and inconsistent A collection of antibodies designed to combine with a single antigen site (specific) can be manufactured known as monoclonals.

8-12 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein How can blood be used as evidence? Blood samples – Can be analyzed to determine BLOOD TYPE and DNA, which can be matched to possible suspects. Blood droplets – Can be analyzed to give clues to the location of a WOUND, movement of a VICTIM, and type of INJURY. Blood spatter – Can be analyzed to determine PATTERNS that give investigators clues to how a crime might have happened.

8-13 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Forensics of Blood The criminalist must be prepared to answer the following questions when examining dried blood: 1.Is it blood? 2.From what species did the blood originate? 3.If the blood is of human origin, how closely can it be associated to a particular individual? The determination of blood is best made by means of a preliminary color test.

8-14 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein The Tests - 1 A positive result from the Kastle-Meyer color test is highly indicative of blood. –Hemoglobin causes a deep pink color. Alternatively, the luminol test is used to search out trace amounts of blood located at crime scenes. –Produces light (luminescence) in a darkened area. Microcrystalline tests, such as the Takayama and Teichmann tests, depend on the addition of specific chemicals to the blood so that characteristic crystals will be formed.

8-15 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein The Tests - 2 Once the stain has been characterized as blood, the precipitin test will determine whether the stain is of human or animal origin. The precipitin test uses antisera normally derived from rabbits that have been injected with the blood of a known animal to determine the species origin of a questioned bloodstain. Once it has been determined that the bloodstain is of human origin, an effort must be made to associate or dissociate the stain with a particular individual. DNA analysis has allowed forensic scientists to associate blood to a single individual.

8-16 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Figure 8-5

8-17 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Stain Patterns of Blood The crime scene investigator must remember that the location, distribution, and appearance of bloodstains and spatters may be useful for interpreting and reconstructing the events that produced the bleeding. Surface texture and the stain’s shape, size, and location must be considered when determining the direction, dropping distance, and angle of impact of a bloodstain.

8-18 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein 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. Angle of Impact – The angle at which a blood droplet strikes a surface. 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 form the spatter; can help determine the direction from which the blood traveled.

8-19 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Bloodstain Pattern Analysis How can an investigator use bloodstain patterns to analyze a crime scene? Location and description of individual stains and patterns Direction a blood droplet was traveling by calculating angles of impact Area of origin of blood source or sources The type of object used in attack (edged, blunt, firearm, etc.) Minimum number of blows The positions of the victim, suspect, and objects during events The sequence of events Evidence from bloodstain pattern analysis is not usually powerful enough on its own to convict someone of a crime, but it can be useful in supporting other types of evidence found at a scene.

8-20 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein 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 –Low, medium, or high impact spatters, cast-off, arterial spurting, expiratory blood blown out of the nose, mouth, or wound. Transfer or Contact Bloodstains –The pattern created when a wet, bloody object comes in contact with a target surface; may be used to identify an object or body part. –Wipe pattern from an object moving through a bloodstain or swipe pattern from an object leaving a bloodstain. Images from

8-21 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Stain Patterns of Blood Surface texture is of paramount importance. In general, the harder and less porous the surface, the less spatter results. The direction of travel of blood striking an object may be discerned because the pointed end of a bloodstain always faces its direction of travel. The impact angle of blood on a flat surface can be determined by measuring the degree of circular distortion. At right angles the blood drop is circular, as the angle decreases, the stain becomes elongated. The origin of a blood spatter in a two-dimensional configuration can be established by drawing straight lines through the long axis of several individual bloodstains. The intersection or point of convergence of the lines represents the origin point.

8-22 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Heredity and Paternity The transmission of hereditary material is accomplished by means of microscopic units called genes, located on chromosomes. Alternative forms of genes that influence a given characteristic (such as eye color or blood type) are known as alleles. Paternity testing has historically involved the A-B-O blood typing system, along with blood factors other than A-B-O. Currently, paternity testing has implemented DNA test procedures that can raise the odds of establishing paternity beyond 99 percent.

8-23 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Testing for Seminal Stains Many of the cases sent to a forensic laboratory involve sexual offenses, making it necessary to examine exhibits for the presence of seminal stains. The best way to locate and at the same time characterize a seminal stain is to perform the acid phosphatase (an enzyme secreted into seminal fluid) color test. –A purple color indicates acid phosphatase enzyme. Semen can be unequivocally identified by either the presence of spermatozoa or of p30, a protein unique to seminal plasma. Forensic scientists can successfully link seminal material to an individual by DNA typing.

8-24 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein 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.

8-25 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein 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.