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Chapter 1: Forensic Biology: A
Subdiscipline of Forensic Science
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Forensic Science is the application of science
to matters of Law.
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Is uniquely cross-disciplinary and draws upon:
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Chemistry
Biology
Physics
Geology
Medicine
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“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
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Date: March 27, 1977
Tenerife, Canary
Location:
Islands
Boeing B-747Aircraft: 121 / Boeing B747-206B
Reg: N736PA/PH-BUF
Pan American
Airline: World Airways /
KLM
Flight No:
1736 / 4805
Fatalities:
644 : 583
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'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.
DNA Science Matches Crash Victims With Families
By MATTHEW PURDY
Published: November 30, 1996
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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
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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
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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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Lab Director
Administration
Biology
Criminalistics
Chemistry
Toxicology
Comparative
Evidence
Controlled
Substances
Toxicology
Trace
Evidence
Clandestine
Labs
Alcohol
Quality Assurance
Arson
Forensic Biology by Richard Li
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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
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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
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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)
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County District Attorney crime labs in California:
 Sacramento County (Sacramento)
 Kern County (Bakersfield)
 Santa Clara County (San Jose)
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City Police Dept crime labs in California:
 El Cajon
 Los Angeles
 San Francisco
 Huntington Beach
 Oakland
 Long Beach
 San Diego
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Gas chromatography-mass spectrometer
Which unit of a crime lab would have this?
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Capillary electrophoresis unit for Forensic DNA profiling
Which unit of a crime lab would have this?
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Tissue samples from a deceased person, suspect, or crime victim.
Which unit of a crime lab would process these and for what purpose?
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A comparison microscope for ballistic analysis.
Which unit of a crime lab would have this?
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Scanning electron microscope used in gunshot residue analysis.
Which unit of a crime lab would have this?
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Forensic Pathology
 Autopsies used to determine:
▪ Cause of death
▪ Time of death
▪ Manner of death:
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Natural
Homicide
Suicide
Accident
Undetermined
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Forensic Pathology Facility.
Run by Coroner’s or Medical Examiner’s Office
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Histological specimens from an autopsy may be sent
to a crime lab for toxicological testing.
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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
After death,
blow flies infest
dead bodies
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Forensic Odontology
 Use characteristics of teeth, alignment, and
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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
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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)
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In it’s more common, narrower definition, is
the application of serological and DNA
testing in matters of Law.
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Includes:
 Forensic serology
▪ Finding and identifying biological stains and materials
 Forensic DNA analysis
▪ Generating DNA profiles from biological stains and
materials
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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
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History:
 Antigen polymorphism
 Protein polymorphism
 DNA polymorphism
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Antigen Polymorphism
 1900 Karl Landsteiner discovered ABO blood
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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
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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
 Prone to degradation
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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 (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
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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
▪ Can match a suspect to crime scene with absolute certainty
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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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