Introduction to Forensic Science

Chapter 1 - Notes

I. Introduction

A. What is Science? A. Derived from the Latin verb meaning

“to Know” B. Science is a way of knowing C. A systematic acquisition of

knowledge that can be measured precisely

“If they don’t depend on true evidence, scientists are no better than gossips”

- Penelope Fiztgerald (British author)

B. Discovery Science and Induction

A. Discovery science = verifiable observations and measurements

1. often discover by accident 2. often give rise to inductive

conclusions

B. Example-

1. Fleming, 1928, accidentally discovered that fungi produce chemicals that kill bacteria. This led to the discovery of Penicillin

c. Induction

1. Inductive conclusion = a generalization that summarizes many concurrent observations 1. Goes from specific observations to a

generalization 2. Example: “all living things are made

up of cells” arose from 2 centuries of biologists discovering cells in all biological specimens observed

C. Scientific Method

A. As a result of asking questions and seeking explanations

B. Is a formal process of inquiry, consisting of a series of steps

C. Hypothetico-deductive reasoning is used to answer the questions 1. hypothesis = educated guess 2. deductive = flows from the general to

the specific instead of specific to general 3. usually takes the place of predictions

about outcomes of experiments or observations

4. is “If . . . Then” logic

d. Deduction and Scientific Method

1. Observation : My flashlight doesn’t work

2. Question : What’s wrong with my flashlight?

3. Hypothesis: The flashlight’s batteries are dead

4. Prediction : If this hypothesis is correct 5. Experiment: and I replace the batteries

with new ones 6. Predicted Result: then the flashlight

should work

E. If the result supports the hypothesis, make additional predictions and test them

F. If the result does not support hypothesis, revise hypothesis or pose new one

D. Forensic Science

A. Forensic = (adj.) Pertaining to legal proceedings or public debate

B. Forensic Science = application of science to the processes of law and involves the collection, examination, evaluation, and interpretation of evidence

c. Application of . . .

1. Biological 2. Physical 3. Chemical 4. Medical 5. Behavioral Science 6. . . . To questions of evidence of

law

II. History of Forensic Science

A. Early History A. BCE – Evidence of fingerprints in

early painting and rock carvings B. 700s – Chinese used fingerprints to

establish identity C. Ca. 1000 – His Duan Yu D. 1609 – Systematic document

examination E. 1784 – First documented use of

physical matching

B. 1800s

A. First recorded use of questioned document analysis

B. The development of tests for the presence of blood in a forensic context

C. A bullet comparison used to catch a murderer

D. The first use of toxicology in a jury trial

E. The development of the first crystal test for hemoglobin

F. The development of a presumptive test for blood

G. First use of photography for the identification of criminals and documentation of evidence and crime scenes

H. First recorded use of fingerprints to solve a crime

I. Development of first microscope with a comparison bridge

c. 1900s

A. Establishment of popular practice of using the comparison microscope for bullet comparison

B. Development of ABO blood typing technique

C. Invention of first interference contrast microscope

D. Development of luminal

E. Study of voiceprint identification F. Invention of Breathalyzer G. Use of heated headspace

sampling technique for collecting arson evidence

H. Development of scanning electron microscope

I. Identification of polymorphic nature of red blood cells

J. Enactment of Federal Rules of Evidence

K. Evaluation of gas chromatograph and mas spectrometer

L. Development of PCR technique M. DNA profiling test N. DNA introduced in criminal courts O. Daubert et al. v. Merrell Dow P. DNA database

D. Important individuals in development of forensic science

A. Mathieu Orfila (1787-1853) – considered the “father” of forensic toxicology

B. Alphonse Bertillon (1853-1914) – developed first system of personal identification

C. Francis Galton (1822-1911) – developed methodology for fingerprinting

D. Leone Lattes (1887-1954) – developed techniques to ID ABO blood groups

E. Calvin Goddard (1891-1944) – expert in ballistic analysis

F. Albert Osborn (1858-1946) – document examination

G. Walter McCrone (1916-2002) – instrumental in using and perfecting microscope use in forensic analysis

H. Hans Gross (1847-1915) – application of scientific disciplines to field of criminal investigation

I. Edmond Locard (1877-1966) – Locard Exchange Principle = “The exchange of materials between 2 objects that occurs whenever 2 objects come into contact with one another”

III. Crime Labs and Their Role in Forensic Science

A. At present there are about 320 crime labs in the US

B. This growth has led to the advent of DNA profiling

C. The Big 8

A. FBI – Federal Bureau of Investigation i. Biggest in Justice Department, limited

to 200 crimes, training, lab supportB DEA - Drug Enforcement Agency i. Best at strategy, surveillance, joint

ops

C USMS – United States Marshall Service i. Provide security and transport for

whole system

D. INS – Immigration and Naturalization Service i. Less detective than others, are

apprehension specialists E. ATF – Bureau of Alcohol, Tobacco

and Firearms i. Treasury counterpart to FBI

F. IRS – Internal Revenue Service i. Tax related, anything with underground

economy

G. USCS – United States Customs Service i. Large import/export, contraband,

porno duties H. USSS – United States Secret

Service i. Secret service, VIP protection,

counterfeiting and fraud

D. Crime Labs

A. Function to train police investigators as to what constitutes physical evidence and how it should be collected, preserved, etc.

B. Analyze this evidence

c. Basic Services

I. Physical Science Unit – chemistry, physics, and geology; sometimes drug ID, soil and mineral analysis and examination of trace evidence

II. Biology Unit – DNA, blood, hairs, fibers and botanicals

III. Firearms Unit – ballistics and tools IV. Documents Unit – handwriting and

typewriting V. Photography Unit – document scenes

and analysis

D. Optional Services

Toxicology Latent Fingerprints Polygraph Voiceprint Analysis Evidence Collection

E. Other Services

i. Pathology – medical dissection and examination of a body in order to determine the cause of death 1. Autopsy – performed to establish the

cause and manner of death

A. Natural B. Homicide C. Suicide D. Accidental E. Undetermined

2. Stages of decomposition

A. Rigor mortis – the medical condition that occurs after death and results in the shortening of muscle tissue and the stiffening of body parts in the position they are in when death occurs

B. Livor mortis – The medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground

C. Algor mortis – Postmorten changes that cause a body to lose heat

Anthropology – age, sex, race, etc.

Entomology – insects to determine time of death

Psychiatry

Odontology – dental records

Engineering

E. Problems of Crime Labs

A. Chain of Custody – three sources of error i. Evidence has to be discovered ii. It has to be collected iii. It has to be transported to the lab

where it is logged in, assigned an identification number, placed in storage, and kept from mingling with other evidence

B. Labs must be free of contaminants

C. Tests must be performed properly and documented

D. Evidence transported back into storage

E. Reports written on analysis of evidence

F. Accreditation Process

A. Quality control manual B. Quality assurance manual C. Lab testing protocol D. Program for proficiency testing –

workers up to standards

G. In general, attacks on labs come in 3 categories

A. Tampering B. Contamination C. Substitution (mistakes)

IV. Role of Forensic Scientist

A. Analysis of Physical Evidence

a. Must be aware of demands and constraints imposed by judicial system

b. Evidence/Science must be admissible in court

C. Frye v. US (1923)

i. Court must decide if procedure, technique or principles are “generally accepted” by a meaningful segment of relevant scientific community

d. Federal Rules of Evidence – more flexible standards for evidence

e. Daubert v. Merrel Dow (1993) i. Frye standard is not an absolute pre-

requisite to admissibility of evidence ii. Guidelines

1. can technique/theory be (been) tested 2. has technique/theory been subject to

peer review and publication 3. techniques potential rate of error 4. existence and maintenance of standards 5. has theory/method attracted acceptance

within relevant scientific community

B. Provide Expert Testimony

A. Expert Witness = an individual whom the court determines possess knowledge relevant to the trial that is not expected of the average layperson

C. Furnishing Training in the Proper Recognition, Collection, and Preservation of Physical Evidence