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Forensic Biology by Richard Li

Chapter 1: Forensic Biology: A Subdiscipline of Forensic Science. Forensic Biology by Richard Li. What is Forensic Science?. Forensic Science is the application of science to matters of Law. Is uniquely cross-disciplinary and draws upon: Chemistry Biology Physics Geology Medicine.

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Forensic Biology by Richard Li

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  1. Chapter 1: Forensic Biology: A Subdiscipline of Forensic Science Forensic Biologyby Richard Li

  2. What is Forensic Science? • Forensic Science is the application of science to matters of Law. • Is uniquely cross-disciplinary and draws upon: • Chemistry • Biology • Physics • Geology • Medicine

  3. What is Forensic Science? • “Matters of Law” include: • Crimes • Homicide, sexual assault, burglary, etc. • Disputes among individuals • Wrongful death, patents, family law, etc. • Establishing rights • Immigration, land disputes • Investigation of disasters • Natural and man-made

  4. What is Forensic Science?

  5. What is Forensic Science?

  6. What is Forensic Science?

  7. What is Forensic Science?

  8. 'Baby 81' Reunited With Parents After DNA Tests End Agonizing Post-Tsunami Custody Dispute http://www.cbsnews.com/stories/2005/02/02/world/main671047.shtml CBS/AP)  "Baby 81," the infant claimed by nine couples after he miraculously survived the tsunami, was reunited with his parents Wednesday in the joyous conclusion to an agonizing custody battle that captured hearts around the world.Smiling with relief, Jenita Jeyarajah took the baby, dressed in blue, from a doctor's arms in a courtroom packed with onlookers after the judge said DNA tests confirmed the baby is her 4-month-old son Abilass.

  9. DNA Science Matches Crash Victims With Families By MATTHEW PURDY Published: November 30, 1996

  10. What is Forensic Science? • Unique roles of forensic scientists: • Assist in recognition and collection of physical evidence • Analyze and evaluate the evidence using a variety of scientific approaches • Interact with the legal system • Assist attorneys and law enforcement • Testify in Court

  11. What is Forensic Science?

  12. What Forensic Science is NOT • Forensic Science is NOT a branch of Law Enforcement! • Forensic scientists do not interrogate and arrest suspects • Forensic scientists do not usually investigate crime scenes • Crime Scene units of law enforcement agencies do most of the work of crime scene investigation • Samples from the crime scene are sent to forensic scientists at crime labs for analysis

  13. Forensic Laboratory Services • Common Disciplines: • Crime scene investigation • Latent print examination • Forensic Biology • Controlled substance analysis • Postmortem toxicology • Questioned document examination • Firearms, toolmark, and other impression evidence examination • Explosives and fire debris examination • Transfer (Trace) evidence examination Forensic Biology by Richard Li

  14. Forensic Laboratory Services

  15. Forensic Laboratory Services

  16. Forensic Laboratory Services

  17. Forensic Science Services Organization of Sacramento County Crime Lab Lab Director Administration Criminalistics Chemistry Toxicology Quality Assurance Biology Comparative Evidence Controlled Substances Clandestine Labs Toxicology Trace Evidence Alcohol Arson Forensic Biology by Richard Li

  18. Forensic Laboratory Services • Most crime labs in U.S. are public sector laboratories operated and funded by the governments and jurisdictions they serve • California: • 30 public crime labs • 11 California Department of Justice • 9 County Sheriff’s Crime Labs • 7 City Police Department Crime Labs • 3 County District Attorney Crime Labs Forensic Biology by Richard Li

  19. Forensic Laboratory Services • California Dept of Justice crime labs: • Sacramento • Ripon • Watsonville • Richmond (does the most hiring in California) • Santa Barbara • Chico • Fresno • Riverside • Santa Rosa • Eureka • Redding

  20. Forensic Laboratory Services • County Sheriff’s Dept crime labs in California: • Alameda County (San Leandro) • Fresno County (Fresno) • Contra Costa County (Martinez) • Los Angeles County (Los Angeles) • Orange County (Santa Ana) • San Bernardino County (Rancho Cucamonga) • San Mateo County (San Mateo) • San Diego County (San Diego) • Ventura County (Ventura)

  21. Forensic Laboratory Services • County District Attorney crime labs in California: • Sacramento County (Sacramento) • Kern County (Bakersfield) • Santa Clara County (San Jose)

  22. Forensic Laboratory Services • City Police Dept crime labs in California: • El Cajon • Los Angeles • San Francisco • Huntington Beach • Oakland • Long Beach • San Diego

  23. Forensic Laboratory Services Gas chromatography-mass spectrometer Which unit of a crime lab would have this?

  24. Forensic Laboratory Services Capillary electrophoresis unit for Forensic DNA profiling Which unit of a crime lab would have this?

  25. Forensic Laboratory Services Tissue samples from a deceased person, suspect, or crime victim. Which unit of a crime lab would process these and for what purpose?

  26. Forensic Laboratory Services A comparison microscope for ballistic analysis. Which unit of a crime lab would have this?

  27. Forensic Laboratory Services Scanning electron microscope used in gunshot residue analysis. Which unit of a crime lab would have this?

  28. Other Forensic Science Services • Forensic Pathology • Autopsies used to determine: • Cause of death • Time of death • Manner of death: • Natural • Homicide • Suicide • Accident • Undetermined

  29. Other Forensic Science Services Forensic Pathology Facility. Run by Coroner’s or Medical Examiner’s Office

  30. Other Forensic Science Services Histological specimens from an autopsy may be sent to a crime lab for toxicological testing.

  31. Other Forensic Science Services • Forensic Anthropology • Identification and examination of human skeletal remains • Examination may reveal: • Individual’s origin • Sex • Approximate age • Race • Presence of skeletal injuries

  32. Other Forensic Science Services • Forensic Entomology • The study of insects in relation to a criminal investigation • Estimating time of death • Stages of insect development After death, blow flies infest dead bodies

  33. Other Forensic Science Services • Forensic Odontology • Use characteristics of teeth, alignment, and overall structure • Bite mark analysis • Useful in the identification of victims whose bodies are unrecognizable • Most people have dental records • Dentition and dental history are unique to each person

  34. Forensic Biology • In it’s broadest definition, is the application of the theory and practice of any branch of biological science in matters of law • Body fluid and DNA analysis (molecular biology) • Autopsy (anatomy and physiology) • Entomology (invertebrate zoology; insects) • Botany (plants) • Odontology (dentistry) • Physical anthropology (study of bones)

  35. Forensic Biology • In it’s more common, narrower definition, is the application of serological and DNA testing in matters of Law. • Includes: • Forensic serology • Finding and identifying biological stains and materials • Forensic DNA analysis • Generating DNA profiles from biological stains and materials

  36. Forensic Biology • Goal is to generate individual identifying characteristics from biological evidence: • Link suspect to crime scene • Link suspect to victim • Link multiple crimes to a single suspect • History: • Antigen polymorphism • Protein polymorphism • DNA polymorphism

  37. Forensic Biology • Antigen Polymorphism • 1900 Karl Landsteiner discovered ABO blood group antigens: A, B, AB, O • Many other blood antigens discovered later; 29 systems now known • Discrimination low: 10-3 • Non-secretors • Prone to degradation

  38. Forensic Biology • Protein polymorphism • By 1980 approximately 100 had been discovered • Combined with blood groups lowered the probability of a match between two unrelated individuals • Prone to degradation

  39. Forensic Biology • DNA polymorphism • 1984 Sir Alec Jeffreys • Variable Number Tandem Repeat (VNTR) • Used in 1986 to solve murder case in the United Kingdom • Able to reveal far greater individual variability • The probability of two unrelated individuals having the same DNA profile is low (10-9) • DNA from crime scene can be linked to a suspect with a high degree of certainty • Requires lots of cells to work • Does not work well on degraded DNA samples

  40. Forensic Biology • DNA polymorphism • Mid 1980’s Polymerase Chain Reaction (PCR) technique • Amplifies tiny quantities of DNA • Greatly increased the sensitivity of forensic DNA • Single Nucleotide Polymorphisms (SNP) • Amplified Length Polymorphisms (AFLP) • Short Tandem Repeat (STR) • Greatly increased the sensitivity of the assay • Highly variable • Can match a suspect to crime scene with absolute certainty

  41. Forensic Biology • DNA polymorphism • 1995- First national DNA database for criminal investigations established in the United Kingdom • 1998- First in United States • Combined DNA Index System (CODIS) • 13 STR loci • Mitochondrial DNA (mtDNA) • Maternally inherited • Useful when nuclear DNA is degraded or in limited amounts • E.g. shed hairs • Polymorphic markers at the Y chromosome • Paternally inherited • Paternity cases • Multiple contributors in sexual assault cases

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