Forensic Serology. Chapter 8

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1 Forensic Serology Chapter 8

2 Chronological History of Blood 2500 B.C. Egyptians bloodletting Cure disease 500 B.C. Greeks Vein v. Artery 175 A.D. Galen Circulatory paths 1628 Sir William Harvey Continuous circulation 1659 Antony Leeuwenhoek Blood cells and microscope 1795 Philip Syng Physick 1 st transfusion

3 1874 Sir William Osler Discovered platelets 1901 Karl Landsteiner A,B,O types 1902 Alfred on Decastello AB type 1922 Percy Oliver Blood Donor Service 1925 Humans are secretors 1935 Mayo Clinic Store blood

4 1937 Dr. Bernard Fantus Blood Bank 1900s Kastle Presumptive blood test 1940 Landsteiner Rh protein 1940 American Red Cross Blood banks for WW Dr. Paul Beeson Described transfused hepatitis

5 1959 Dr. Max Perutz Structure of hemaglobin 1971 Dr. Blumberg Antibody detection 1982 Dr. Alec Jeffreys DNA profile from WBC 1984 Dr. Robert Gallo Identified AIDS

6 Nature of Blood Highly complex mixture of cells, enzymes, proteins, and inorganic substances. Plasma the fluid portion of blood composed principally of water. Solid materials suspended Red blood cells (erythrocytes) (RBC) White blood cells (leukocytes) (WBC) Platelets Antigens on the surface of red blood cells and responsible for bloodtype characteristics.

7 Blood Typing 300+ blood antigen systems identified 1 million+ protein binding sites! A-B-O and Rh systems are the most important. Blood type determines the antigens present Rh factor is determined by the D antigen.

8 Agglutination -specific antibody reacts with specific antigen to form clumps Example: anti-b serum is added to type B blood, they will immediately react.

9 Frequencies of Blood Types O+ 1 in 3 persons O- 1 in 15 persons A+ 1 in 3 persons A- 1 in 16 persons B+ 1 in 12 persons B- 1 in 67 persons AB+ 1 in 29 persons AB- 1 in 167 persons

10 Serology Describes 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 concept of specific antigen-antibody reactions has been applied to immunoassay techniques for the detection of drugs of abuse in blood and urine.

11 Immunoassay A number of immunological assay techniques are commercially available for detecting drugs Example: Enzyme-Multiplied Immunoassay Technique (EMIT) Used by toxicologists because of its speed and high sensitivity for detecting drugs in urine. Antibodies that will bind to a specific drug are added to the subject s urine Other immunoassay procedures also available RadioImmunoAssay (RIA) Uses drugs labeled with radioactive tags

12 EMIT assay

13 Antigen-Antibody Reaction Polyclonal Antibodies When an animal is injected with an antigen, its body will produce a series of different antibodies, which are designed to attack some particular site on the antigen of interest Stimulating production of drug antibodies.

14 Steps required to produce monoclonal antibodies. More uniform and specific collection of antibodies designed to combine with a single antigen site

15 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.

16 Bloodstains Wet blood has more value than dried blood because more tests can be run. Alcohol and drug content Blood begins to dry after 3-5 minutes of exposure to air Changes color towards brown and black Blood at the crime scene can be in the form of pools, drops, swipe, wipe, smears, or crusts Pools of blood have more evidentiary value in obtaining a wet sample Blood crusts need to be tested with crystalline methods to make sure it's blood

17 Bloodstains Drops of blood tell the height and angle from which the blood fell Blood which fell perpendicular to the floor from a distance of 0-2 feet will make a circular drop with slightly frayed edges Drops from a higher distance would have more pronounced tendrils fraying off the edges (a sunburst pattern) A blood smear on the wall or floor tells the direction of force of the blow The direction of force is always in the direction towards the tail, or smaller end, of the smear, or splatter The largest area of the smear is the point of origin (a wave cast-off pattern)

18 Blood Splatter Analysis When blood falls from a height or at a high velocity, it can overcome its natural cohesiveness and form satellite droplets. When it falls onto a less-than-smooth surface, it can form spiking patterns around the drops. Forensic Science: Fundamentals & Investigations, Chapter 8 18

19 Bloodstains Refrigerated red blood cells have a shelf life of about 42 days The serum containing white blood cells can be refrigerated much longer, almost up to a year DNA can be extracted from blood (if white blood cells are present) sperm bone marrow tooth pulp hair roots.

20 DNA from Blood Blood is commonly used in DNA testing 1. Blood samples are collected from the victim, defendant, and crime scene 2. WBC are separated from RBC 3. DNA is extracted from the nuclei of WBC 4. A restrictive enzyme is used to cut fragments of the DNA strand 5. DNA fragments are put into a bed of gel with electrodes at either end 6. Electric current sorts DNA fragments by length 7. An absorbent blotter soaks up the imprint; it is radioactively treated, and an X-ray photograph (called an autoradiograph) is produced

21 The Kastle-Meyer Test A positive result from the Kastle-Meyer color test is highly indicative of blood. Hemoglobin causes a deep pink color. The steps 1. Wet cotton swab and rub on bloodstain 2. Drop ethyl alcohol on swab 3. Drop phenolphthalein (phph) onto swab 4. Drop hydrogen peroxide(h2o2) onto swab 5. Determine color

22 Workings of Kastle-Meyer Water loosens RBC from stain Ethyl Alcohol exposes hemoglobin Phph serves as the O2 acceptor, color indicator H2O2 substrate for the perioxidase

23 Other Tests The luminol test used to search out trace amounts of blood located at crime scenes Produces light (luminescence) in a darkened area Microcrystalline tests, Takayama and Teichmann tests, depend on the addition of specific chemicals to the blood so that characteristic crystals will be formed Precipitin test Gel Diffusion

24 The precipitin test

25 Gel Diffusion

26 A-B-O vs DNA Prior to the advent of DNA typing, bloodstains were linked to a source by A-B-O typing and the characterization of polymorphic blood enzymes and proteins. This approach has now been supplanted by the newer DNA technology. DNA analysis has allowed forensic scientists to associate blood and semen stains to a single individual.

27 Stain Patterns of Blood The crime scene investigator must remember Location Distribution 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.

28 Stain Patterns of Blood Surface texture is of paramount importance. The harder and less porous the surface = less spatter 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. 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.

29 Illustration of stain convergence on a two-dimensional plane. Convergence represents the point from which the stains emanated. Courtesy Judith Bunker, J. L. Bunker & Assoc., Ocoee, FL

30 Categories of Blood Stains Passive Transfer Projected

A recognizable image of all or a portion of the original surface

31 Transfer Bloodstains A transfer bloodstain is created when a wet, bloody surface comes in contact with a secondary surface. A recognizable image of all or a portion of the original surface may be observed in the pattern, as in the case of a bloody hand or footwear.

32 Passive Bloodstains Passive bloodstains are drops created or formed by the force of gravity acting alone.

33 Projected Bloodstains Projected bloodstains are created when an exposed blood source is subjected to an action or force, greater than the force of gravity. (Internally or Externally produced) The size, shape, and number of resulting stains will depend, primarily, on the amount of force utilized to strike the blood source.

Projected Bloodstains Arterial Spurt/Gush Bloodstain pattern(s) resulting from blood exiting the body under pressure from a breached artery Cast-off Stains Blood released or thrown from a

34 Projected Bloodstains Arterial Spurt/Gush Bloodstain pattern(s) resulting from blood exiting the body under pressure from a breached artery Cast-off Stains Blood released or thrown from a blood-bearing object in motion Impact Spatter Blood stain patterns created when a blood source receives a blow or force resulting in the random dispersion of smaller drops of blood. Velocity affects stain pattern

35 Impacted Spatter Medium Velocity Low Velocity High Velocity

36 Blood Splatter Analysis Six Patterns Describe each of these: a. passive drops b. arterial gushes c. splashes d. smears e. trails f. pools

37 Directionality of Bloodstains When a droplet of blood strikes a surface perpendicular (90 degrees) the resulting bloodstain will be circular. That being the length and width of the stain will be equal. 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 pointed end of the bloodstain ( tail ) will always point in the direction of travel.

39 SIN < = Width (a) 1.5cm Length (c) 3.0cm SIN < = 0.5 < = 30 degrees

40 Heredity & Paternity The transmission of hereditary material is accomplished 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.

41 Testing for Seminal Stains Many of the cases involve sexual offenses Necessary to examine exhibits for the presence of seminal stains Perform the acid phosphatase (an enzyme secreted into seminal fluid) color test Semen can be unequivocally identified by either the presence of spermatozoa p30 (a protein unique to seminal plasma) Link seminal material to an individual by DNA

42 Acid Phospatase Test A purple color indicates acid phosphatase enzyme. A screening test for semen by determining acid phosphatase content Seminal fluid contains high concentrations of acid phosphatase Other body fluids and extraneous foreign materials have very low concentrations High values of acid phosphatase on vaginal aspirate or wash fluid from stains, render positive identification of semen, even if the male is aspermic.

43 An antibody antigen antibody sandwich or complex is seen as a colored band. This signifies the presence of PSA in the extract of a stain and positively identifies human semen.

44 PSA testing by electrophoresis.

45 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.

46 Physical Evidence from the Victim Pubic combings Pubic hair standard/reference sample External genital dry-skin areas Vaginal swabs and smear Cervix swab Rectal swabs and smear Oral swabs & smear Head hairs Blood sample Fingernail scrapings All clothing Urine specimen

47 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.

Objectives. You will understand: Blood

Objectives. You will understand: Blood Objectives You will understand: That an antibody and an antigen of different types will agglutinate, or clump, when mixed together. That the significance of the evidence depends on a characteristic s relative