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Biological Forensics

Biological Forensics. Laboratory Exercise 12. Forensics Lab Objectives. Learn the definition of forensic science. Examine ways biological information can be used to solve crimes, and see examples of this in today’s society. Forensic Science.

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Biological Forensics

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  1. Biological Forensics Laboratory Exercise 12

  2. Forensics Lab Objectives • Learn the definition of forensic science. • Examine ways biological information can be used to solve crimes, and see examples of this in today’s society.

  3. Forensic Science • Definition:The application of the tools of science, as well as specific scientific facts, to help solve legal problems • Goal:the determination of the cause, location, and time of death

  4. Some Uses of Forensics • Identify potential suspects whose DNA may match evidence left at crime scenes • Exonerate persons wrongly accused of crimes • Identify crime and catastrophe victims • Establish timing and circumstances of a crime http://www.rit.edu/~vjrnts/forensics/labs/lab1/lab1pix.html

  5. Categories of Forensics • DNA Evidence • Forensic Entomology • Forensic Serology • Forensic Odontology Bluebottle blow fly

  6. Forensic Fingerprinting Fingerprint counting number of typica • Forensic Anthropology Radiocarbon dating of the Dead Sea Scrolls • Forensic Art Composite art, image modification, age progression, post-mortem reconstruction and demonstrative evidence

  7. Forensic Pathology • Forensic Psychiatry • Forensic Toxicology • Bloodstain Pattern Analysis • Forensic Photography

  8. Biological Forensics Use of Entomology (the study of insects) Use of Molecular biology (DNA analysis)

  9. Entomology • Use of the insects, and their arthropod relatives that inhabit decomposing remains to aid legal investigations • Compare the insect to the different stages of their life cycle http://www.ext.nodak.edu/extpubs/ansci/horse/eb55-2.htm

  10. Common Insects Found on Carrion Blow Flies (order Diptera) Some comon larvae or "maggots" found on human remains Life cycle of a typical blowfly

  11. Beetles (order Coleoptera) larvae shown here are from four different beetle families American carrion beetle, Necrophila americana sexton beetle, Nicrophorus orbicollis

  12. Molecular Forensics • Use of identifying characteristics of molecules in our cells to aid legal investigations • Compare the DNA and/or blood type of crime scene evidence to that of suspects, or use this information to identify a victim.

  13. Two main methods of Molecular Forensics • PCR (Polymerase Chain Reaction) • Blood typing

  14. PCR (Polymerase Chain Reaction) • Developed in 1987 • Amplify one molecule of DNA into billions of copies in a few hours • Identifies an individual based on microscopic amount of evidence • 99% accuracy rate

  15. Genetic Variation • Most genes have small sequence differences between individuals • Occur every 1350 bp on average • Some of these polymorphisms may affect: • How well the protein works • How the protein interacts with another protein or substrate • A gene is a unit of inheritance

  16. C C C C C C C C N C C N N C N C C N C N C N N C Hydrogen Bonds H H H O H C H H N N Thymine C Adenine H N H O H H N H H H N Cytosine O C H Guanine N H O N H H

  17. Double-Stranded DNA

  18. PCR DNA

  19. Some Interesting Uses of DNA Forensic Identification • ID 9/11 victims • ID plane crash victims • ID Missing children • DNA Shoah Project • Tomb of the Unknowns • Son of Louis XVI and Marie Antoinette • Nicholas Romanov • Peruvian Ice Maiden • African Lemba Tribesman • Super Bowl XXXIV Footballs and 2000 Summer Olympic Souvenirs • Study migration patterns • Poached animals • DNA banks for endangered species

  20. Forensic Serology • Historical methods of identifying and individualizing blood and other body fluids • Antigen-Antibody reactions • Enzyme-Substrate reactions

  21. HISTORY • In 1901 Dr. Karl Landsteiner discovered blood typing. • awarded a Noble Prize.

  22. Blood Artery White blood cells Platelets Red blood cells

  23. Blood Plasma-55% Buffy coat-<1% Formed elements-45%

  24. ANTIGENS

  25. ANTIGENS b a b a b b a a a b b a b b a a

  26. AGGLUTINATION

  27. Blood being tested Serum Anti-A Anti-B Type AB(contains agglutinogens A and B; agglutinates with both sera) RBCs Type A(contains agglutinogen A; agglutinates with anti-A) Type B(contains agglutinogen B; agglutinates with anti-B) Type O(contains no agglutinogens; does not agglutinate with either serum) Figure 17.16

  28. Can this blood be associated to a particular individual? MAYBE!?!

  29. Blood Type & Rh How Many Have It Frequency O Rh Positive 1 person in 3 37.4% O Rh Negative 1 person in 15 6.6% A Rh Positive 1 person in 3 35.7% A Rh Negative 1 person in 16 6.3% B Rh Positive 1 person in 12 8.5% B Rh Negative 1 person in 67 1.5% AB Rh Positive 1 person in 29 3.4% AB Rh Negative 1 person in 167 .6%

  30. In Class Assignment • Analyze 4 suspects blood types • Compare it to blood found on the murder weapon. • Determine the murderer.

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