Chapter 1: Forensic Biology: A Subdiscipline of Forensic Science

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?

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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

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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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