Ch-1-Intro-S

Chapter 1

Introduction

Forensic ScienceRichard Saferstein

© 2009 Pearson Education, Upper Saddle River, NJ 07458.

All Rights Reserved.2

Definition In its broadest definition, forensic science is the

application of science to criminal and civil laws. The subject matter of this book emphasizes the

application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system.

Forensic science owes its origins to individuals such as Bertillon, Galton, Lattes, Goddard, Osborn, and Locard, who developed the principles and techniques needed to identify or compare physical evidence.




History Mathieu Orfila—the father of forensic toxicology. Alphonse Bertillion—devised the first scientific

system of personal identification in 1879. Francis Galton—conducted the first definitive

study of fingerprints and their classification. Leone Lattes—developed a procedure to

determine blood type from dried bloodstains. Calvin Goddard—used a comparison microscope

to determine if a particular gun fired a bullet. Albert Osborn—developed the fundamental

principles of document examination.




History Walter McCrone—utilized microscopy and other

analytical methodologies to examine evidence. Hans Gross—wrote the first treatise describing

the application of scientific principles to the field of criminal investigation.

Edmond Locard—incorporated Gross’ principles within a workable crime laboratory.

Locard’s Exchange Principle—states that when a criminal comes in contact with an object or person, a cross-transfer of evidence occurs.

Sir Alec Jeffreys—developed the first DNA profiling test in 1984.




The Crime Lab The development of crime laboratories in the

United States has been characterized by rapid growth accompanied by a lack of national and regional planning and coordination.

At present, approximately 350 public crime laboratories operate at various levels of government—federal, state, county, and municipal.




The Crime Lab

The ever increasing number of crime laboratories is partly the result of the following: Supreme Court decisions in the 1960s

responsible for police placing greater emphasis on scientifically evaluated evidence.

Crime laboratories inundated with drug specimens due to accelerated drug abuse.

The advent of DNA profiling.




Technical Support The technical support provided by crime

laboratories can be assigned to five basic services. Physical Science Unit incorporates the principles

of chemistry, physics, and geology to identify and compare physical evidence.

Biology Unit applies the knowledge of biological sciences in order to investigate blood samples, body fluids, hair, and fiber samples.

Firearms Unit investigates discharged bullets, cartridge cases, shotgun shells, and ammunition.




Technical Support Document Examination Unit provides the

skills needed for handwriting analysis and other questioned-document issues.

Photography Unit applies specialized photographic techniques for recording and examining physical evidence.




Technical Support Optional Services by Full-Service Labs

Toxicology Unit examines body fluids and organs for the presence of drugs and poisons.

Latent Fingerprint Unit processes and examines evidence for latent fingerprints.

Polygraph Unit conducts polygraph or lie detector tests.

Voiceprint Analysis Unit attempts to tie a recorded voice to a particular suspect.

Crime Scene Investigation Unit dispatches specially trained personnel to the crime scene to collect and preserve physical evidence.




SPECIAL FORENSIC SCIENCE SERVICES

Forensic Psychiatry is an area in which the relationship between human behavior and legal proceedings is examined.

Forensic Odontology involves using teeth to provide information about the identification of victims when a body is left in an unrecognizable state. Also investigates bite marks.

Forensic Engineering is concerned with failure analysis, accident reconstruction, and causes and origins of fires or explosions.

Forensic Computer and Digital Analysis Unit examines digital evidence.




The Scientific Method Formulate a question worthy of

investigation. Formulate a reasonable hypothesis to

answer the question. Test the hypothesis through

experimentation. Upon validation of the hypothesis, it

become suitable as scientific evidence.




Skills of a Forensic Scientist A forensic scientist must be skilled in applying

the principles and techniques of the physical and natural sciences to the analysis of the many types of evidence that may be recovered during a criminal investigation.

A forensic scientist may also provide expert court testimony.

An expert witness is an individual whom the court determines possesses knowledge relevant to the trial that is not expected of the average person.




Skills of a Forensic Scientist The expert witness is called on to evaluate

evidence based on specialized training and experience that the court lacks the expertise to do.

The expert will then express an opinion as to the significance of the findings.

Forensic scientists also participate in training law enforcement personnel in the proper recognition, collection, and preservation of physical evidence.




The Frye Standard The Frye v. United States decision set

guidelines for determining the admissibility of scientific evidence into the courtroom.

To meet the Frye standard, the evidence in question must be “generally accepted” by the scientific community.




“Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized

scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs. We think the systolic blood pressure deception test has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made.”

Part of the Frye Decision




Frye Not Absolute However, in the 1993 case of Daubert v.

Merrell Dow Pharmaceutical, Inc., the U.S. Supreme Court asserted that the Frye standard is not an absolute prerequisite to the admissibility of scientific evidence.

Trial judges were said to be ultimately responsible as “gatekeepers” for the admissibility and validity of scientific evidence presented in their courts, as well as all expert testimony.




Daubert Facts Plaintiffs claimed birth defects from Bendectin Dow moved for summary judgment on expert

testimony Plaintiff’s expert said “could” cause birth defects Plaintiff’s experts used “unorthodox” methods Trial court ruled in Dow’s favor Ninth Circuit Court of Appeal affirmed Supreme Court agreed to hear to establish

standard




The Supreme Court Test Three part test for admissibility of evidence

Evidence must be relevant (Rules 401 &402) Evidence must be reliable, based on science

(Rules 702) Opinion of the scientific expert must be grounded in

methods and procedures of science Must apply to a body of known facts accepted as

truths on good grounds In other words – supported by appropriate

validation




Daubert Criteria For Admissibility Whether the scientific technique or theory

can be tested. Whether the technique has been subject to

peer review and publication. The techniques potential rate of error. Existence and maintenance of standards . Whether the scientific theory or method

has attracted widespread acceptance within a relevant scientific community.




Disciplines facing challenges Fingerprints

Faced some challenges in US District Court in Philadelphia

January 2002, excluded. Judge reversed himself in March 2002 after government filed a motion to reconsider.

Questioned Documents Studies being done on lay vs. trained document

examiners Some issues arise in any science where an “error rate”

cannot be established




Efforts in Setting Standards Establishment of Scientific Working Groups Set standards for education, training, and methods Examples

SWGDRUG – hosted by DEA SWGMAT – trace evidence such as hairs, fibers SWGFAST – fingerprints SWGDE – digital evidence SWGGUN – firearms and toolmarks SWGDAM – DNA SWGDOC – questioned documents




Quality in the Laboratory

Certificationof Examiners

Accreditationof Laboratories

Standardizationof Methods

AS

TMAB

CASCLD-LAB




Evidence Collection Training

Many crime laboratories have “evidence technicians,” trained by the crime lab staff, on 24-hour call for evidence collection at crime scenes.

Training ensures all pertinent evidence will be recognized and collected properly.

Where no formal training exists, familiarity can be gained through lectures, tours of the lab, and evidence collection manuals.

Ch-1-Intro-S

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