Transcript Forensic Biology by Richard Li - Fayetteville State University

Chapter 1: Forensic Biology
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Common Disciplines:
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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
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Forensic Pathology
 Autopsies used to determine exact cause of death
 Time of death
 Manner of death:
▪ Natural
▪ Homicide
▪ Suicide
▪ Accident
▪ Undetermined
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Forensic Anthropology
 Identification and examination of human skeletal
remains
 Examination may reveal:
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Individual’s origin
Sex
Approximate age
Race
Presence of skeletal injuries
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Forensic Entomology
 The study of insects in relation to a criminal
investigation
 Estimating time of death
▪ Stages of insect development
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Forensic Odontology
 Participate in the identification of victims whose
bodies are unrecognizable
 Use characteristics of teeth, alignment, and
overall structure
 Bite mark analysis
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History
 Antigen polymorphism
 Protein polymorphism
 DNA polymorphism
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Antigen Polymorphism
 1900 Karl Landsteiner discovered ABO blood
groups
 A, B, AB, O
 Forensic serology
 Useful in excluding a suspect
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Protein polymorphism
 By 1980 approximately 100 had been discovered
 Combined with blood groups lowered the
probability of a match between two unrelated
individuals
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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
 DNA from crime scene can be matched to a
suspect
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DNA polymorphism
 Mid 1980’s Polymerase Chain Reaction (PCR)
technique
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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
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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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