The History of DNA Forensics

April 18, 2005

What is DNA?

DNA is the chemical substance which makes up our chromosomes and controls all inheritable traits (eye, hair and skin color)

DNA is different for every individual except identical twins

DNA is found in all cells with a nucleus (white blood cells, soft tissue cells, bone cells, hair root cells and spermatozoa)

Half of a individual’s DNA/chromosomes come from the father & the other half from the mother.

DNA Review:

DNA is a double-stranded molecule. The DNA strands are made of four

different building blocks. An individual’s DNA remains the

same throughout life. In specific regions on a DNA strand

each person has a unique sequence of DNA or genetic code.

Repeated DNA Sequences

VNTR’s--Tandemly repeated DNA sequences.

Interspersed Transposable Elements SINES LINES

Cutting Variable DNA Sections

Father: DNA is a long,long,long long molecule that is tightly wound.

Mother: DNA is a long,long molecule that is tightly wound.

Restriction Enzymes are proteins that cut DNA molecules at specific cut sites.

The History of Forensic DNA Analysis Resembles a War.

Laboratories Legal System (Prosecutors /

Defense Attorneys) Media Coverage

Conventional Blood Typing

Used for more than 50 years Utilized ABO blood typing groups Identified genetic variations in

blood proteins, tissue specific proteins and serum protein types

Major problem is that the conventional blood protein markers are not found in semen.

Development of DNA Analysis Techniques (1970’s)

RFLP (Restriction Fragment Length Polymorphism)

Southern Blot

Restriction Fragment Length Polymorphism

Restriction Enzymes (biological catalysts) cut DNA whenever they encounter a specific DNA sequence.

Gel electrophoresis separates the fragments of DNA according to their length.

Size Separation of DNA by Gel Electrophoresis

Total DNA Gel Electrophoresis

Restriction Enzymes

Southern Blot

A short segment of DNA that is complementary to a portion of the desired DNA fragments is labeled with a radioactive atom.

This probe binds to the fragment of interest on the gel electrophoresis.

Visualized using X-ray film.

A Schematic Representation of RFLP and Southern Blot of a Single-locus VNTR

History of DNA Analysis (1980’s)

In 1980 David Botstein and others used RFLP to construct a human gene map.

Used genetic variations as markers

Kary Mullis Invented PCR Methods (1984)

Polymerase Chain Reaction amplifies short specific regions of DNA

PCR is an in vitro technique that can yield millions of copies of desired DNA

Does not use radioactivity

PCR Amplifies DNA Exponentially

In 1984, Alec Jeffreys developed “DNA Fingerprinting.”

Was searching for disease markers Applied the technique to personal

identification Demonstrated that the DNA could

be retrieved from old dried blood stains

Applied the technique to high-profile forensic tests

A Typical DNA Profile

The Pitchfork Case (1986 & 1987) Jeffreys was consulted in the case of the

murder and rape of two British schoolgirls.

Suspect cleared from analysis of semen samples at the scene and blood samples from the suspect.

“Blooded” 4583 men Analysis of blood sample from Colin

Pitchfork provided a match.

Pennsylvania v Pestinikas (1986)

First PCR case done in the United States

Involved allegations of switching body parts at a funeral home

Commercial Development of Forensic DNA Testing in the United States:

Lifecodes Corporation—Founded in 1982 in Valhalla, NY as diagnostic company. Began performing forensic DNA testing in 1987

Cellmark—The US branch of Britain’s Imperial Chemical Industries opened in Germantown, MD in 1987. Performed the testing for the prosecutor in the Simpson case.

Trial of Accused Rapist Tommy Lee AndrewsNovember 3, 1987

First case in the U.S. to identify a criminal by DNA

Trial held in Orlando, Florida A scientist from Lifecodes and a

biologist from M.I.T. testified that semen left on the victim matched Andrew’s DNA (1 in 10 billion)

November 6, 1987 jury returned a guilty verdict.

The two major private companies raced each other to the courtroom.

In a shroud of secrecy and an environment of expediency they disregarded the usual methods of testing new scientific methods Publication and Peer Review Standardization Replication Evaluation of Performance

DNA analysis was considered an “infallible” prosecution tool.

“You can’t argue with science.” a juror in Queens

“[DNA evidence] is the single greatest advance in the search for truth since the advent of cross-examination.” Judge Joseph Harris of Albany, NY

DNA analysis was considered an “infallible” prosecution tool.

“In rape cases, when the semen has been matched with the defendant’s and the chance that it came from another person is 33 billion to 1, you don’t need a jury.” Robert Brower, defense attorney.

New York v Castro

First successful defense against DNA analysis

Jose Castro, janitor in a nearby building, was accused of the stabbing deaths of Vilma Ponce and her two-year old daughter, Natasha.

New York v Castro

Lifecodes Corporation reported that the blood found on Castro’s watch matched that of Vilma Ponce with a frequency of 1:189,200,000 in the Hispanic population.

Defense mounted the first successful attempt to have DNA evidence excluded.

New York v Castro

Two defense and two prosecution witnesses agreed that Lifecodes had failed to use generally accepted scientific techniques. Their data was poor and they did not follow procedures for interpreting the data

Castro later confessed and pled guilty to the murders.

The FBI and The Royal Canadian Mounted Police Set Up DNA Laboratories

1987 FBI with NIH began collaborative research to establish DNA identification techniques

In late 1988 FBI set up their own laboratory at their Pennsylvania Avenue headquarters

RCMP also set up their own DNA laboratory.

FBI Worked With Pioneers in the Field

They used four different DNA probes GeneLex Dr. Raymond White of Howard

Hughes Medical Center Lifecodes Cellmark

DNA probes and primers are the

key patented biomolecules used to identify the individual genetic variability.

The FBI and RCMP brought standardization to the indusdry. Established detailed laboratory

protocols Performed validation studies Cut through the competitive nature

that clouded the environment of the testing methods and tools

Defense Strategy

In 1989, National Association of Criminal Defense Lawyers (NACDL) set up a DNA Task Force.

Headed by Barry Scheck, a professor at Benjamin N. Cardozo Law School and Peter Neufeld, a private attorney in Manhattan

Defense Strategy

Tried to reopen all the convictions involving evidence processed by Lifecodes

Escalated the conflict surrounding DNA testing

Launched a public relations campaign critical of DNA typing

In 1990 Scheck and Neufeld Prepare for United States vs Yee.

Three members of Hell’s Angels motorcycle gang of Cleveland Ohio were accused of killing David Hartlaub thinking he was a member of a rival gang

The victim was shot 14 times with a MAC 10 machine gun.

Blood Evidence on the Scene

Most was determined to be that of the victim

Some belonged to one of the defendants

Theory—a ricocheting bullet had hit one of the suspects.

Prosecution Expert Witnesses

Thomas Caskey, Baylor College of Medicine

Kenneth Kidd, Yale geneticist Bruce Budowle, FBI DNA scientist

Defense Expert Witnesses

Richard Lewontin, geneticist from Harvard

Daniel Hartl, geneticist at Washington University

Eric Lander, mathematician and geneticist at M.I.T.

Defense Argued:

FBI’s published articles on matching criteria were “ambiguous” and “inconsistent.”

Prosecution Countered:

In spite of disputes over match criteria, the multi-probe match produced a highly likelihood that the specimens came from two different people.

United States vs Yee

DNA matches were admitted as evidence at the trial and at the appeal.

The documents from the FBI would later find their way into the courtroom.

The National Academy of Science’s National Research Council (NCR) Report

A federal study intended to be the definitive study on the problems of forensic DNA

The most contended issue--How to calculate statistical probability The frequencies of sub-groups could

differ widely from that in the larger population

NCR Report—DNA Technology in Forensic Science (1992) Criticized:

Ceiling principle No population geneticists or

staticians on the panel Inconsistencies Did not address paternity cases or

PCR

NCR Report—DNA Technology in Forensic Science

The report was to be the final word in clarifying the role of DNA forensics.

This document is often cited by defense lawyers in arguing of the exclusion of DNA evidence.

The Media and DNA Forensics

First the Media proclaimed that the “new technology was a miracle.”

It recorded it’s “glowing victories.” Followed by giving opponents to

DNA analysis a venue for airing objections and charges (many of which were unfounded and unchallenged)

The Media and DNA Forensics

The Washington Post headline read, “Panel Backs DNA Tests as Crime Evidence.”

Nature Published Articles Exploring Forensic DNA

Alec Jeffreys announced his methods in Nature.

“DNA fingerprinting dispute laid to rest” Budowle and Lander Oct. 27, 1994

“Lander and Budowle declare that

after 400 technical papers, 100 scientific conferences, three sets of DNA analysis guidelines, 150 court cases, and an exhaustive three-year study by the National Research Council—’The DNA fingerprinting wars are over.’”

1994

National Research Council reconvened to try to rectify the deficiencies of their first report.

The trial of the century convened: “Dollars v DNA” or California v OJ Simpson.

Summary

Forensic DNA testing was developed rapidly by short-sighted commercial interests

Standards were not developed as quickly as necessary

Prosecution oversold DNA evidence Expert witnesses had a vested

interest in fueling the controversy.

Summary

Sensational and inaccurate media coverage spread misinformation about DNA.

The judicial system is sometimes indifferent to choices that could expedite justice.

The Media and DNA Forensics

The DNA Technology in Forensic Science report strongly endorsed the continued use of DNA typing in the courts.

The New York Times front page article headline read “U.S. Panel Seeking Restriction on Use of DNA in Courts.”

Where is Forensic DNA Analysis Today?

Forensic labs have implemented a process of peer review, self-regulation and accreditation

DNA analysis has freed over 156 convicts. The Innocence Project at Yeshiva University is run by Barry Sheck and Peter Neufeld.

Where is Forensic DNA Analysis Today?

Paternity testing. Historical case of Thomas Jefferson

as the likely father of children of slave, Sally Hemmings.

Resolved questions surrounding the disputed descendent of the Czar Nicholas II

Terms to Know

ABO Blood Typing RFLP Southern Blot PCR Kary Mullis Alec Jeffreys DNA

Fingerprinting

DNA typing DNA profiling Probe Primer

Resources

Textbook: Chapters 1, 2 & 3 pp. 8,9, 17 & 21-31.

DNA in the Courtroom; Coleman & Swenson, GeneLex Press 1994.

DNA Technology in Forensic Science; Committee on DNA Technology in Forensic Science—National Research Council; National Academy Press 1992