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Forensic Science

Chapter 1: Introduction

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Forensic science Applies the knowledge and technology of

science for the definition and enforcement of laws• Criminal justice

• Provide accurate and objective information

• Food safety and quality• Medications• Water purity• Pesticide use• Air pollution

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Limited definition For this class, Forensic science is the application of

science to those criminal and civil laws that are enforced by police.

We will deal with crime-scene and evidence analysis• Not medicine, psychology, etc.

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Criminalistics Another term for forensic science Specifically applied to crime solving

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History and development of forensic science Made popular by Sir Arthur Conan Doyle

• Author of Sherlock Holmes stories Often imagined scientific detection

methods before they were actually discovered• Predicted ability to identify blood stains with a

chemical that reacts only with hemoglobin

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Mathieu Orfila 1787 – 1853 Father of forensic toxicology 1814 – Studied detection of poisons and

their effects on animals

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Aphonse Bertillon 1853 – 1914 1879 – Anthropometry Used series of body measurements for

identification Replaced by fingerprinting in early 1900s Still used as part of facial recognition

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Francis Galton 1822 – 1911 1892 – fingerprint analysis and

identification

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Leone Lattes 1887 – 1954 1915 – procedure for determining blood

group (A, B, AB, or O) of dried bloodstains

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Calvin Goddard 1891 – 1955 Used comparison microscope to

examine bullets from crime scenes and from suspects’ weapons

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Albert S. Osborn 1858 – 1946 1910 – Questioned Documents –

document examination procedures• Still used as a reference

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Walter C. McCrone 1916 – 2002 Using microscopes to examine evidence

• Hairs, fibers, organic material, etc.

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Hans Gross 1847 – 1915 1893 – advocated the application of

science to criminal investigations

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Edmond Locard 1877 – 1966 1910 – started police lab in Lyons, France Believed that every criminal can be connected

to a crime by dust particles carried from the crime scene

Proved this in a series of well-publicized investigations• Led to the formation of other police laboratories

throughout Europe

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Locard’s Exchange Principle The exchange of materials between two

objects that occurs whenever two objects come into contact with one another.

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FBI Lab Established in 1932

• J. Edgar Hoover Now the world’s largest forensic science

lab Model for labs around the US and in

other countries Training Center – 1981 – training and

research into new forensic science methods

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LAPD lab Oldest in the US 1923

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Labs in the US Local and independent

• Federal• State• County• City

California has unified somewhat into a network, exchanging information and expertise

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Labs in Britain National system of regional labs Police pay a fee for services of labs More efficient? More “fair”?

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Growth in crime labs Number of labs greatly increases in past

35 years Court decisions favoring scientific

evidence• Miranda warning

Modern technology – DNA Increase in crime rate – especially drugs

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Federal labs FBI DEA (Drug Enforcement Administration) ATF (Bureau of Alcohol, Tobacco,

Firearms, and Explosives) USPS (Postal service)

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Basic lab services Physical Science Biology Firearms Document Examination Photography

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Physical Science Chemistry, Physics, Geology Chemicals Trace elements Drug identification

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Biology DNA Compare hairs and fibers Compare botanicals – wood and plants

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Firearms Unit Guns Ammunition Gunshot residue Tool marks

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Document Examination Handwriting and typewriting Paper and ink analysis Indented writings Damaged documents (burned, etc.)

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Photography Record evidence Digital imaging IR, UV, and X-ray photography Prepare courtroom exhibits

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Optional lab services Toxicology Fingerprints Polygraph Voiceprint Evidence collection

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Toxicology Find drugs or poisons in tissues and

fluids

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Fingerprints Processing and examining fingerprints

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Polygraph Lie detectors Users must be trained in interrogation Not purely scientific – results not always

reliable

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Voiceprint Compare voices on different recordings Individuals produce unique sound and

speech patterns

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Evidence collection Trained personnel to collect evidence

from the scene

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Reality check A criminalist will normally work in only

one area – the scene OR the lab If they are in the lab, they usually are in

one specific area, they don’t know about everything

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Analyzing evidence Scientists must be aware of court rulings

on procedures and techniques

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The Frye Standard Named after Frye v. United States

(1923)• When the lie detector test was rejected

The technique in question must be accepted by a meaningful segment of the scientific community

Must be “generally accepted”

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Federal rules of Evidence More flexible Daubert v. Merrell Dow Pharmaceutical, Inc.

(1993) The trial judge can act as a “gatekeeper” and

determine whether or not the science is based on a reliable foundation• Has it been tested?• Has it been reviewed and published?• What is its rate of error?• Are there standard operating procedures?• Is it widely accepted?

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KumhoTire Co., Ltd. V. Carmichael 1999 “gatekeeping” role applies to all expert

testimony• “technical”• “other specialized”

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Coppolino v. State (Florida) Cause of death was overdose of a drug that

had never before been detected in the human body

Medical examiner’s explanation satisfied judge, despite lack of other experimental data

Allowed testimony• “Society need not tolerate homicide until there

develops a body of medical literature about some particular lethal agent.”

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Expert witness An individual whom the court determines

possesses knowledge relevant to the trial that is not expected of the average person

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Expert knowledge Can be acquired through

• Experience• Training• Education• Combination of above

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Forensic science experts Usually don’t have degrees in forensic

science• Chemistry• Biology• Physics• Geology

Rely on training and years of experience

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Credibility Expert witnesses must prove their

knowledge by citing degrees and experience

They may also be asked questions to prove or disprove their expertise

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Offering opinions Ordinary witnesses must only present

facts that come from personal knowledge Expert witnesses may present opinions

on the significance of scientific findings Must present only the truth – including

possible errors in the methods

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Evidence collection Specially-trained technicians Police officers must also be trained

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Forensic Pathology Investigation of sudden, unnatural,

unexplained, or violent deaths Autopsy – the medical dissection and

examination of a body in order to determine cause of death• Natural• Homicide• Suicide• Accident• undetermined

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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

Appears within 24 hours, gone in 36 hours

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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

Begins immediately and lasts for up to 12 hours

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Algor Mortis Postmortem changes that cause a body

to lose heat About 1 to 1 ½ degrees F each hour Depends on location and size of body,

clothing, and weather conditions

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Forensic Anthropology Identification and examination of skeletal

remains Can reveal sex, age, race, and injuries Facial reconstructions

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Forensic Entomology Study of insects Used to estimate time of death Depends on temperature

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Forensic Psychiatry Evaluate behavioral disorders Determine competency Help develop suspect profiles

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Forensic Odontology Identification through dental records Bite mark analysis

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Forensic Engineering Failure analysis Accident reconstruction Causes and origins of fires and

explosions