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Forensic Biologyby Richard Li
Chapter 1: Forensic Biology: A Subdiscipline of Forensic Science
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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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“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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What is Forensic Science?
What is Forensic Science?
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What is Forensic Science?
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What is Forensic Science?
Date: March 27, 1977 Location
:Tenerife,
Canary Islands
Aircraft:Boeing B-747-121 / Boeing B-
747-206B
Reg: N736PA/PH-BUF
Airline:Pan American
World Airways / KLM
Flight No: 1736 / 4805
Fatalities: 644 : 583
'Baby 81' Reunited With Parents After DNA Tests End Agonizing Post-Tsunami Custody Dispute
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.
http://www.cbsnews.com/stories/2005/02/02/world/main671047.shtml
DNA Science Matches Crash Victims With FamiliesBy MATTHEW PURDYPublished: November 30, 1996
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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What is Forensic Science?
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What is Forensic Science?
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 analysis13
What Forensic Science is NOT
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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
15Forensic Biology by Richard Li
Forensic Laboratory Services
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Forensic Laboratory Services
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Forensic Laboratory Services
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Forensic Science Services
19Forensic Biology by Richard Li
Lab Director
Administration
Biology Criminalistics Chemistry Toxicology Quality Assurance
Comparative Evidence
Trace Evidence
Arson
Controlled Substances
Clandestine Labs
Toxicology
Alcohol
Organization of Sacramento County Crime Lab
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
20Forensic Biology by Richard Li
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
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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)
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Forensic Laboratory Services
County District Attorney crime labs in California: Sacramento County (Sacramento) Kern County (Bakersfield) Santa Clara County (San Jose)
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Forensic Laboratory Services
City Police Dept crime labs in California: El Cajon Los Angeles San Francisco Huntington Beach Oakland Long Beach San Diego
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Kenya: Population 40 million
1 crime lab
California: Population 36 million
30 crime labs
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"Security" booth, Government Chemist Crime Lab, Nairobi Kenya (2010)
Forensic Laboratory Services
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Gas chromatography-mass spectrometerWhich unit of a crime lab would have this?
Forensic Laboratory Services
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Capillary electrophoresis unit for Forensic DNA profilingWhich unit of a crime lab would have this?
Forensic Laboratory Services
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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?
Forensic Laboratory Services
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A comparison microscope for ballistic analysis.Which unit of a crime lab would have this?
Forensic Laboratory Services
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Scanning electron microscope used in gunshot residue analysis.Which unit of a crime lab would have this?
Other Forensic Science Services
Forensic Pathology Autopsies used to determine:▪ Cause of death▪ Time of death ▪ Manner of death:▪ Natural▪ Homicide▪ Suicide▪ Accident▪ Undetermined
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Other Forensic Science Services
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Forensic Pathology Facility.Run by Coroner’s or Medical Examiner’s Office
Other Forensic Science Services
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Histological specimens from an autopsy may be sent to a crime lab for toxicological testing.
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
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Other Forensic Science Services
Forensic Entomology The study of insects in relation to a
criminal investigation Estimating time of death▪ Stages of insect development
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After death, blow flies infest
dead bodies
Other Forensic Science ServicesForensic 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 person37
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)
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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 materials39
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 40
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
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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
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Forensic Biology
DNA polymorphism 1984 Sir Alec Jeffreys ▪ Variable Number Tandem Repeat (VNTR)▪ Used in 1986 to solve murder case in the
United Kingdom (The Blooding) 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 43
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
certainty44
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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