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Blood and Blood Splatter in Forensics

Learn about the importance of blood typing, forensic biology, blood composition, and splatter analysis in criminal investigations.

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Blood and Blood Splatter in Forensics

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  1. Drill • Why is blood typing a class evidence? • How is forensics biology different from forensics serology?

  2. Drill • Define whole blood. • What are the formed elements of blood? Objective(s) • Explain and do a Blood Spatter analysis. • Collection, Preservation & Packaging of Biological Evidence

  3. Drill • Define antibodies & antigens. How are they different? • Name two things that can be determine from a blood splatter pattern. • Name & describe 3 out of the 6 splatter patterns.

  4. Blood & Physiological Fluid Evidence

  5. Chapter 8Blood and Blood Splatter • explain the composition of blood • describe the function of blood cells • determine the blood type of a blood sample • conduct a blood splatter analysis • examine wounds and describe the nature of the weapon • find and process blood evidence

  6. Introduction and History • Blood typing can provide ______________; whereas DNA profiling can provide ________________________. • A _______________pattern can give information about the truthfulness of an account by a witness or a suspect. • It also can provide information about the ______________ of the blood, the angle and velocity of impact, and type of weapon used. • Our understanding of blood began in _______ times and continues to grow today.

  7. Forensics biology Preliminary examination of biological evidence in blood transfer and sexual assault cases, much that goes on the ___________________________. Forensics Serology – Preliminary examination and genetic typing of biological evidence in blood transfer and sexual assault cases ________________analysis was available.

  8. Review • What is the difference between forensics biology and forensics serology? • What kind of evidence can blood typing provide for court?

  9. Nature of Blood 1. Only _________________ tissue in the body. 2. Made up of several cell types; ________________(erythrocytes) __________(leukocytes), and __________. 3. _______________ – blood serum protein 4. _______________________ - antibodies

  10. Composition of Blood • _______________carries cells and plasma—the fluid with hormones, clotting factors, and nutrients. • ________________carry oxygen to the body’s cells and carbon dioxide away. • _________________fight disease and foreign invaders and, alone, contain cell nuclei. • ______________aid in blood clotting and the repair of damaged blood vessels.

  11. Function 1. ________________________through out the body. 2. Transfers _________________ throughout the body. 3. _________________. 4. ____________________ Amount of cells in blood ______ million RBC per cubic millimeter ____________ WBC per cubic millimeter ___________ mg/mL albumin ___________ mg/mL Immunoglobulin's

  12. Review • Name two functions of blood? • What are the parts of blood with their function?

  13. Tube of blood is drawn and allowed to ______ for a few minutes for ________________. • Blood will ____________ and become a dark red and fall to the bottom. • _______ is on _____ is yellowish and contains dissolved proteins and other compounds. • ________ – same as serum but contains the clotting protein.

  14. Blood Typing—Proteins 42% 12% 3% 43% of the population in the United States (of which 85% is Rh+) Blood typing is _________ and less expensive than DNA profiling. It produces class evidence but can still link a suspect to a crime scene or exclude a suspect.

  15. Review • What are the four blood types for humans? • Which type is most common? • Can a blood type convict a suspect?

  16. Blood Typing—Antibodies; Additional Proteins and Enzymes • ____________ are proteins secreted by white blood cells that attach to antigens to destroy them. • ____________ are foreign molecules or cells that react to antibodies. • ____________ are complex proteins that catalyze different biochemical reactions. • Many enzymes and proteins have been found in the blood that are important for identification purposes.

  17. Blood Typing—Probability and Blood Types • Given the frequency of different genes within a population, it is possible to determine the probability that a particular blood type will appear in a _____________________________. • To determine the probability of two separate events, it is necessary to multiply their individual probabilities. • By identifying the additional proteins in the blood evidence sample, investigators can limit the size of a suspect population and help identify a suspect.

  18. Blood Splatter • In 1939 the meaning of the splatter pattern was first analyzed. • When a wound is inflicted, a blood _____________ pattern may be created. • It takes a _____________ of blood stains to make a blood splatter pattern. • The pattern can help to _______________the events surrounding a shooting, stabbing, or beating.

  19. Blood Splatter Analysis Analysis of a splatter pattern can aid in determining the: ________________________________. ________________________________. ________________________________. ________________________________.

  20. Blood Splatter Analysis • When blood falls from a height or at a high velocity, it can overcome its natural cohesiveness and form ________________________. • When it falls onto a less-than-smooth surface, it can form ________________around the drops.

  21. Blood Splatter Analysis—Six Patterns Describe each of these: a. ______________ b. ______________ c. ______________ d. ______________ e. ______________ f. ______________

  22. Blood Splatter Analysis—Impact Patterns can help investigators determine the ___________________ of weapon used. • What kind of a pattern is produced by a gun shot? • What kind of a pattern is produced by a hammer blow?

  23. Blood Splatter Analysis—Directionality The _________________ 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?

  24. Blood Splatter Analysis—Location of the Origin of the Blood • Draw straight lines down the axis of the blood splatters. • Where the ____________________, the blood originated.

  25. Review • 1. How can blood splatter determine direction? • 2. How can blood splatter determine location/origin of the blood source?

  26. Crime Scene Investigation of Blood • Search for blood evidence. • If any is discovered, process it determining: • Whether the evidence is ____________. • Whether the blood is _________________. • The blood ___________________. • Interpret the findings: • See if the blood type matches a ________. • If it does not,_____________that suspect. • If it does, decide if ___________is needed

  27. Collection, Preservation & Packaging of Biological Evidence __________________, Exemplar, Reference are known sources of biological evidence. Collected in a ___________________. The ______ of the stopper is an indicator of the _________ used. _______ is most common (enediaminetetraaceiticacia) in a purple top. Can get DNA from many other places; Cheek (Buccal)

  28. Review • How is a known control different from an alternative control? • Why is a blank control used? • Name 2 out a 3 guidelines for crime scene investigation.

  29. Biological Evidence from Scenes _______ items with blood. Fresh or Wet – clean spoonlike utensil. Dried – Cutting, swabbing, scrapping, and elution (dissolving). Ensuring that the evidence is ___________________before it is package and stored in a dry cool place. Package in paper containers that can “___________”, never is an air tight container.

  30. Testing ___________________– specimen from a known source. _____________________– specimen obtained that might be the source of evidence. _____________________– a clean sample containing no specimen.

  31. Forensics Identification of Blood ________________(Screening) - for screening specimens that might contain substances or materials. False-positives or false-negative Ideally preliminary test should give a _________ false negatives to ________ this test as a screening tool.

  32. Testing ______________________– A sample of material on which biological evidence is deposited. ___________________ – unintended or potentially unrecognized, biological material in or on biological evidence, which could cause difficulty in interpreting the results.

  33. Forensics Identification of Blood __________________– More complicated and requires more time than a preliminary test. Entirely specific for the substance or material for which they are intended. A positive confirmatory means it is unequivocal demonstration that the specimen contains the substance or material. No confirmatory test is available for blood – most the analyst can say is “might or could have”.

  34. Forensics Identification of Body Fluids Semen Male reproductive fluid. Spermatozoa – ______ ________ million sperm per milliliter. Seminal Plasma fluid that suspends sperm.

  35. Semen is associated with sexual assault cases. • Somewhere in America, a woman is raped every ____ minutes, according to the U.S. Department of Justice. • In 1995, _______ women were the victims of a rape or sexual assault. (NationalCrime Victimization Survey. Bureau of Justice Statistics, U.S. Department of Justice, 1996.) • Over the last two years, more than _________ women were the victim of a rape or sexual assault. (National Crime Victimization Survey. Bureau of Justice Statistics, U.S.Department of Justice, 1996.) • The FBI estimates that ____ of every _____________ females in the United States were raped last year. (Federal Bureau of Investigation, Uniform Crime Statistics, 1996.)

  36. Approximately______ of victims are raped by husbands or boyfriends, _____ by acquaintances, and _____ by other relatives. (Violence against Women, Bureau of Justice Statistics, U.S. Dept. of Justice, 1994) • The FBI estimates that only ______ of all rapes are reported to the police. U.S. Justice Department statistics are even lower, with only _________ of all rapes or attempted rapes being reported to law enforcement officials.

  37. ____ of every ____ rapes take place in a public area or in a parking garage. • _____ of female victims reported that the offender was a stranger. • _____ of rapes occur between the hours of ___ p.m. and ____ a.m. • At ______of rapists were under the influence of alcohol or drugs. • In _____of rapes, the offender used a weapon. • In _____of rapes, the victim sustained injuries other than rape injuries. • ______ of female rape victims require medical care after the attack.

  38. Semen shines fluoresce brightly when exposed to ________. Preliminary & confirmatory test for semen stains – same as blood testing. ______________________________is a color test for the enzyme produced by the male prostate gland.

  39. Evidence collection and sexual assault cases Rape Kits

  40. Investigation DNA profiling Cases often succeed or fail on the __________ of the parties, since there is rarely a witnesses. Injuries are properly _______________ and helpful in some cases.

  41. Identification of Saliva and Urine Saliva is produced by three gland that empty into the mouth cavity that contain a large amount of _________. Tests for amylase Dyed starch Radial enzyme diffusion ____________ is found in many plants and animals, therefore it is not confirmatory only indicative.

  42. __________ – contains several substance in large quantities. Many animals produce urine, therefore it is considered the same as saliva.

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

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