Lecture 1: Forensic Biology: A Sub-discipline of Forensic Science

Forensic BiologyRichard Li, with additions and edits by Ruth Ballard

Lecture 1: Forensic Biology: A Sub-discipline of Forensic Science

Outline

About your professor Class and Individual characteristics

About this courseCreating a Crime MapWhat is forensic science?Forensic laboratory servicesWhat is forensic biology?History of forensic biology: 1960-

present2

Name: Ballard, RuthHair: BrownEyes: GreenHt: 5’ 2”Wt: 105Occupation: Professor and researcherLast Known Address:Dept of Biological SciencesCalifornia State University, Sacramento

About your Professor

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Class Characteristic: Often covered in white fur

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Identifying Characteristic: DNA profile

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About this course

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DNA breakthroughs in 1990s

+

News coverage

= BIO 150

Naïve new professor

Students watching TV shows

+TV

shows

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Creating a Crime Map

A Crime Map is a visual summary of a crime Becomes a tool for remembering how

everything fits together Helps put biological evidence in context as

you receive it Can be organized in many different

ways This is your opportunity to be creative!

▪ Colored pencils, flow charts, time-lines Submit one per lab pair

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At a minimum should include:Basic information about the crime

▪ Date, time, location▪ Victims▪ Suspect (if identified)▪ Eyewitness reports (to establish probable scenarios)

Evidence collected ▪ When/where/by whom▪ Where it is being stored

Pending or completed analyses by other units What’s available for testing and what’s

missing8


Example on the board You can continue to update your crime map

as the semester progresses Add results of your own lab analyses

Due for grading in lab on week from this coming Friday This week in lab: Introduction Next week in lab: Lab 1 (The Crime Scene:

Setting, Evidence, and Process); Crime map due Use supplementary materials at back of lab

manual as your source of information for the map

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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 (Is this white power cocaine?) Biology (Did the semen come from the suspect?) Physics (How fast was the car going at impact?) Anthropology (Are these bones human?) Medicine (How did this child die?)

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“Matters of Law” include: Crimes

▪ Homicide, sexual assault, burglary, etc. Disputes among individuals

▪ Wrongful death, patents, etc. Establishing rights

▪ Parentage; immigration, land disputes Investigation of disasters

▪ Natural and man-made

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'Baby 81' Reunited With Parents After DNA Tests End Agonizing Post-Tsunami Custody Dispute

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 Document and maintain chain-of-

custody Analyze and evaluate the evidence using

a variety of scientific approaches Interact with the legal system

▪ Assist attorneys (and often law enforcement personnel)

▪ Testify in Court 16


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Typical U.S. courtroom. Where does everyone sit?

NOT a branch of Law Enforcement! Forensic scientists do not interrogate

and arrest suspects Forensic scientists do not usually

investigate crimes▪ Crime Scene units of law enforcement

agencies and forensic medical professionals collect most of the evidence

▪ Evidence from the crime scene is then sent to forensic scientists at crime labs for analysis

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Forensic Laboratory Services

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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

Also see Table 1.1 in textbook


Most crime labs in U.S. are public sector laboratories available only to law enforcement and prosecutors 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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YOU DO NOT NEED TO MEMORIZE THESE!


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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Forensic Laboratory Services There are also private forensic

laboratories Independently test forensic evidence Available to defense attorneys and their

clients as well as the general public 16 private labs in California including

SERI (Richmond CA) Forensic Analytical (Hayward CA) Forensic Laboratory Services (San Luis Obispo) Forensic DNA Consulting (Mountain View)

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Current Model:

Crime Lab

Crime Scene

Prosecution Defense

Courts

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Ideal Model:

Crime Lab

Crime Scen

e

Prosecution

Defense COUR

T


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Gas chromatography-mass spectrometerWhich unit of a crime lab would have this?


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Capillary electrophoresis unit for Forensic DNA profilingWhich 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?

What is Forensic Biology?

Broad Definition: The application of the theory and practice of any branch of the biological sciences to matters of law Pathology (anatomy and physiology) Entomology (invertebrate zoology;

insects) Odontology (dentistry) Physical anthropology (study of bones) Microbiology, botany, wildlife… Body fluids (serology) and DNA

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Forensic Pathology Autopsies used to determine:

▪ Cause of death▪ Manner of death:

▪ Natural▪ Homicide▪ Suicide▪ Accident▪ Undetermined

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Forensic Pathology Facility.Run by Coroner’s or Medical Examiner’s Office


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

What is Forensic Biology?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

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What is Forensic Biology?Forensic Microbiology

Forensic Botany

Forensic Wildlife

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What is Forensic Biology?Narrow Definition: The

application of serological and DNA testing in matters of Law.

Goal is to generate identifying information from biological evidence: DNA Forensic serology

▪ Finding/identifying biological stains and materials

Forensic DNA analysis▪ Generating DNA profiles from biological

stains/materials39

What is Forensic Biology?DNA used to:

Link suspect to crime scene Link victim to crime scene Link suspect to victim Link victim to suspect Link multiple crimes to a single suspect

We’ll learn more about how cells (and DNA) are transferred in Lecture 2

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History of Forensic Biology

Two trends: Dramatically increased level of

probability that a suspect is the source of a crime scene sample (16 orders of magnitude)

Dramatically fewer numbers of cells need for testing▪ Ability to generated DNA profiles from “trace

evidence,” including “contact DNA”

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Important Definitions

Random match probability = RMP Probability of randomly selecting an

individual from the population with the same combination of biological markers as the evidence sample

Power of discrimination = PD = 1/RMP

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Began with discovery of red blood cell surface antigen polymorphisms 1900 Karl Landsteiner discovered ABO

blood group antigens Developed by Lattes into ABO blood

typing Immediate applications in medicine

(transfusions) First applied to forensic casework in

1960s43


Limitations: Not very sensitive (lots of cells needed) Sample must be fresh Non-secretors RMP high; PD low

▪ 49% of Americans have blood type O▪ RMP ~ 0.25 (1 in 4); DP = 4

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Blood protein markersBy 1980 approximately 100 had

been discovered Several used by forensic biologists Combined with ABO antigen system

▪ RMP ~0.001(1 in 1000)▪ PD = 1000

Same limitations as the ABO system but higher PD

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History of Forensic BiologyDNA Fingerprinting

1984 Sir Alec Jeffreys ▪ Used in 1986 to solve murder case in the

United Kingdom (The Blooding) High PD (~109) Still required a large, fresh sample

Large visible blood stain Rape with ejaculation taken soon after crime

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Forensic Biology

Huge breakthrough in 1986: PCR Polymerase chain reaction Allowed “amplification” of low-level DNA

prior to analysis A hundred cells rather than hundreds of

thousands▪ Human cell contains 6 pg DNA▪ DNA fingerprinting: 1 ug needed = 167,000

cells▪ PCR: 100 pg needed = 17 cells

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Size of blood stain needed for DNA Fingerprinting

Size of blood stain needed

for PCR

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trace levels

= Identity assumed

Blood antigens/proteins (1960-1985)

Progress of Forensic Biology 1960-Present

DNA fingerprinting (1985-2000)

STR typing (2000-present)

DQA1-PM (1990-2000)

1E+02 1E+08 1E+141

10

100

1000

10000

100000

Power of Discrimination (1/RMP)

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Documents

Lecture 1: Forensic Biology: A Sub-discipline of Forensic Science