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Chapter 1 Introduction to Forensic Science and the Law


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Chapter 1
Introduction to Forensic Science and the Law

“In school, every period ends with a bell. Every sentence ends with a period. Every crime ends with a sentence.” —Stephen Wright, comedian

Forensic Science

  • The study and application of science to matters of law.

  • Includes the business of providing timely, accurate, and thorough information to all levels of decision makers in our criminal justice system.

  • The word forensic is derived from the Latin “forensis” meaning forum, a public place where, in Roman times, senators and others debated and held judicial proceedings.

Criminalistics vs Criminology

Criminalistics: the scientific examination of physical evidence for legal purposes.

Criminology: includes the psychological angle, studying the crime scene for motive, traits, and behavior that will help to interpret the evidence




  • Evidence is anything that tends to establish or disprove a fact. Evidence can include documents, testimony, and other objects.

Crime Lab—Basic Services

  • Physical Science Unit

  • Chemistry

  • Physics

  • Geology

  • Biology Unit

  • Firearms Unit

  • Document Examination Unit

  • Photography Unit

Crime Lab—Optional Services

  • Toxicology Unit

  • Latent Fingerprint Unit

  • Polygraph Unit

  • Voiceprint Analysis Unit

  • Evidence Collection Unit

Other Forensic Science Services

  • Forensic Pathology

  • Forensic Anthropology

  • Forensic Entomology

  • Forensic Psychiatry

  • Forensic Odontology

  • Forensic Engineering

  • Cybertechnology

Forensic Vocabulary

  • Ballistics- the science that deals with the motion, behavior, and effects of projectiles, most often firearms and bullets.

  • Odontology- examination of bite marks and dental identification of corpses.

  • Pathology- investigation of sudden, unexplained, or violent death.

  • Entomology- the study of insects


  • Forensic psychiatry – there are two major areas of criminal evaluations in forensic psychiatry: competency to Stand trial (CST)

and Mental State at the Time of the Offense (MSO).

Major Crime Laboratories

  • FBI

  • DEA

  • ATF

  • U.S. Postal Service

  • U.S. Fish and Wildlife Service

Crime Lab History

  • First police crime lab in the world was established in France in 1910 by Edmond Locard

  • First police crime lab in the U.S. opened in 1923 in Los Angeles

  • The Scientific Crime Detection Lab was founded in Evanston, Illinois in 1929

  • The first FBI crime lab opened in 1932

Major Developments in Forensic Science History

  • 700s AD—Chinese used fingerprints to establish identity of documents and clay sculptures

  • ~1000—Roman courts determined that bloody palm prints were used to frame a man in his brother’s murder

  • 1149—King Richard of England introduced the idea of the coroner to investigate questionable death

  • 1200s—A murder in China is solved when flies were attracted to invisible blood residue on a sword of a man in the community

  • 1598—Fidelus was first to practice forensic medicine in Italy

  • 1670—Anton Van Leeuwenhoek constructed the first high-powered microscope

  • 1776—Paul Revere identified the body of General Joseph Warren based on the false teeth he had made for him

  • 1784—John Toms convicted of murder on basis of torn edge of wad of paper in pistol matching a piece of paper in his pocket

  • 1859—Gustav Kirchhoff and Robert Bunsen developed the science of spectroscopy.

  • 1864—Crime scene photography developed

  • 1879—Alphonse Bertillon developed a system to identify people using particular body measurements

  • 1896—Edward Henry developed first classification system for fingerprint identification

  • 1900—Karl Landsteiner identified human blood groups

  • 1904—Edmond Locard formulated his famous principle, “Every contact leaves a trace.”

  • 1922—Francis Aston developed the mass spectrometer.

  • 1959—James Watson and Francis Crick discover the DNA double helix

  • 1977—AFIS developed by FBI, fully automated in 1996

  • 1984—Jeffreys developed and used first DNA tests to be applied to a criminal case

People of Historical Significance

Edmond Locard (1877-1966)

  • French professor

  • Considered the father of criminalistics

  • Built the world’s first forensic laboratory in France in 1910

  • Locard Exchange Principle

  • Whenever two objects come into contact with each other, traces of each are exchanged.

Crime Scene Team

  • A group of professional investigators, each trained in a variety of special disciplines.

  • Team Members

  • First Police Officer on the scene

  • Medics (if necessary)

  • Investigator(s)

  • Medical Examiner or Representative (if necessary)

  • Photographer and/or Field Evidence Technician

  • Lab Experts

pathologist serologist

DNA expert toxicologist

forensic odontologist forensic anthropologist

forensic psychologist forensic entomologist

firearm examiner bomb and arson expert

document and handwriting experts fingerprint expert

Scientific Method (as it pertains to criminalistics)

  • Observe a problem or questioned evidence and collect objective data.

  • Consider a hypothesis or possible solution.

  • Examine, test, and then analyze the evidence.

  • Determine the significance of the evidence.

  • Formulate a theory based on evaluation of the significance of the evidence

Complex Reasoning Skills

Necessary to Work Through and Solve Crimes:

  • Deductive and Inductive Reasoning

  • Classifying

  • Comparing and Contrasting

  • Problem Solving

  • Analyzing Perspectives

  • Constructing Support

  • Error Analysis

Laws that Pertain to the U.S. Criminal Justice System

  • The U.S. Constitution

  • Statutory Law

  • Common Law or Case Law

  • Civil Law

  • Criminal Law

  • Equity Law

  • Administrative Law

Forensic Legal Vocabulary

  • Statutory law: legislative acts declaring, commanding, or prohibiting something

  • Case Law or Common law: the body of law made up of judicial opinions and precedents

  • Stare decisis: “to stand by the decision” (Latin), meaning previous legal decisions are to be followed.

  • Civil Law: deals with noncriminal suits brought to protect or preserve a civil or preserve a civil or private right or matter.

  • Criminal Law: regulation and enforcement of rights setting the acceptable limits of conduct in society.

  • Equity Law: preventative law for cases not covered by common law (i.e., a restraining order)

  • Administrative Law: includes rules or laws established by governmental agencies such as the IRS, Social Security and the military.

The Bill of Rights
Gives individuals the right:

  • To be presumed innocent until proven guilty

  • Not to be searched unreasonably

  • Not to be arrested without probable cause

  • Against unreasonable seizure of personal property

  • Against self-incrimination

  • To fair questioning by police

  • To protection from physical harm throughout the justice process

  • To an attorney

  • To trial by jury

  • To know any charges against oneself

  • To cross-examine prosecution witnesses

  • To speak and present witnesses

  • Not to be tried again for the same crime

  • Against cruel and unusual punishment

  • To due process

  • To a speedy trial

  • Against excessive bail

  • Against excessive fines

  • To be treated the same as others, regardless of race, gender, religious preference, country of origin, and other personal attributes

Due Process

  • The government may not take away your life, liberty, or property without following appropriate legal procedures.

  • Probable cause: situation in which a reasonable and prudent person, viewing the available information, would conclude that a crime has been committed by the suspect.

Miranda v Arizona

  • In 1963, Ernesto Miranda, a 23 year old mentally disturbed man, was accused of kidnapping and raping an 18-year-old woman in Phoenix, Arizona. He was brought in for questioning, and confessed to the crime. He was not told that he did not have to speak or that he could have a lawyer present. At trial, Miranda's lawyer tried to get the confession thrown out, but the motion was denied. The case went to the Supreme Court in 1966. The Court ruled that the statements made to the police could not be used as evidence, since Mr. Miranda had not been advised of his rights.

Miranda Rights

The following is the Miranda warning:

  • “You have the right to remain silent. Anything you say can and will be used against you in a court of law. You have the right to speak to an attorney, and to have an attorney present during any questioning. If you cannot afford a lawyer, one will be provided to you prior to any questioning>”

Types of Crimes

  • Infraction

  • Misdemeanor

  • Felony

Forensic Legal Vocabulary

  • Infraction: very minor offense, and not necessarily a crime. Punishable by warnings, tickets and probation.

  • Misdemeanor: a minor crime, less than a felony, usually punished with a fine or confinement other than in prison

  • Felony: a serious crime, such as murder, punishable by more than one year of imprisonment up to execution.

Steps in Pursuing Justice

  • 1. After a crime has been committed, and evidence has been documented, a suspect may be taken into custody.

  • 2. Suspect is booked and informed of Miranda Rights.

  • 3. Within 72 hours they are brought before a judge for an arraignment. The suspect enters their plea of guilty, not guilty, not guilty by reason of insanity, or nolo contendere.

  • 4. A person pleading guilty will be taken to a preliminary (or evidentiary) hearing. No jury is present, and the Judge assigns the sentence.

  • 5. A person pleading not guilty at the preliminary hearing presents evidence to the Judge and the judge determines whether a trial is necessary, sets the trial date and sets the bail.

  • 6. In the case of a felony, a grand jury will be in place of a preliminary hearing and the jury will hear the evidence and decide whether the suspect should be indicted.

  • 7. A defendant may choose to plea bargain with the prosecutor instead of going to trial, or they will tried by a jury to determine guilt or innocence.

Forensic Legal Vocabulary

  • Booking: a police procedure following arrest. Includes fingerprinting, a photograph, and basic information about the suspect.

  • Arraignment: the first act in a criminal proceding in which the defendant is brought before the court to hear charges and enter a plea.

  • Nolo Contendere: latin for “no contest”, the defendant doesn’t actually admit to guilt, but accepts the punishment as if they were guilty.

  • Preliminary hearing: determines whether a trial is necessary according to evidence presented.

  • Bail: money put up to guarantee that the defendant will appear in court as directed. A bondsman will pay the bail for a fee of 10% of the bail. If the defendant doesn’t appear at court, bounty hunters will find the suspect to return them to court.

  • Indict: to formally accuse a person of a crime

  • Plea bargain: an agreement in which a defendant pleads guilty to a lesser charge and the prosecutor in return drops the more serious charges to avoid the time and cost of a trial.

Federal Rules of Evidence

In order for evidence to be admissible, it must be:

  • Probative—actually prove something

  • Material—address an issue that is relevant to the particular crime

Admissibility of Evidence

1923 Frye v. United States

  • Scientific evidence is allowed into the courtroom if it is generally accepted by the relevant scientific community. The Frye standard does not offer any guidance on reliability. The evidence is presented in the trial and the jury decides if it can be used.

1993 Daubert v. Dow

Admissibility is determined by:

  • Whether the theory or technique can be tested

  • Whether the science has been offered for peer review

  • Whether the rate of error is acceptable

  • Whether the method at issue enjoys widespread acceptance.

  • Whether the opinion is relevant to the issue

The judge decides if the evidence can be entered into the trial.

Facets of Guilt

Try to prove:

  • Means—person had the ability to do the crime

  • Motive—person had a reason to do the crime (not necessary to prove in a court of law)

  • Opportunity—person can be placed at the crime

“If the Law has made you a witness, remain a man (woman) of science.

You have no victim to avenge, no guilty or innocent person to ruin or save.

You must bear testimony within the limits of science.”

—P.C.H. Brouardel



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