Forensic Science

SFS1. Students will recognize and classify various types of evidence in relation to the definition and scope of Forensic Science.

a. Compare and contrast the history of scientific forensic techniques used in collecting and submitting evidence for admissibility in court (e.g. Locard’s Exchange Principle, Frye standard, Daubert ruling).

ESSENTIAL QUESTIONS

1. What is forensic science?2. What is evidence and how is it used by

forensic scientists?3. What are the characteristics of a typical

crime lab?4. Which historical forensic scientists laid the

ground work for modern forensic science?5. What is the importance of Locard’s

Exchange Principle?

ESSENTIAL QUESTIONS

6. What is the basic methodology used by forensic scientists?

7. What are the steps that must be followed in the pursuit of justice?

8. What is the importance of the Federal Rules of Evidence?

9. What is the importance of the Frye Standard?

10.What is the importance of the Daubert Ruling?

Sequence of Events1) Introduction to Forensic Science and the Law2) The Crime Scene3) Fingerprint Analysis4) Hair and Fiber Analysis5) Soil and Glass Analysis6) Handwriting and Document Analysis7) Forensic Pathology8) Forensic Toxicology9) Forensic Serology and DNA Analysis10)Firearms, Toolmarks and Impressions11)Arson and Explosives

Forensic Science is…the application of science to those criminal and civil laws that are enforced in a criminal justice system.

Criminalistics is…

the examination of physical evidence

Forensic scientists use crime labs to help them examine…

EVIDENCE –

anything that tends to establish or disprove a fact • documents• testimony• objects

Forensic Specialties

Anthropology (human remains)

Psychiatry (mind)

Odontology (bitemarks)

Engineering (structural failures)

Computer Technology (data recovery)

Pathology (death)

Geology (earth)

More Specialties

Environmental Science (human effect on earth)

Entomology (insects)

Palynology (pollen & spores)

Polygraphy (lie detector)

Voiceprint Analysis

A forensic scientist’s main job is to study the different types of evidence found at a crime scene, but s/he must also testify as an expert witness, perform scientific research and train others.

Crime Laboratories• There are ~ 350 crime labs in US

– Federal, state, county, and municipal (local)– Most function as part of a police department– Others fall under direction of the prosecutor or

district attorney’s office– Some work with labs of the medical examiner

or coroner– A few are affiliated with universities or exist as

independent agencies in government

• Most labs are maintained by states for regional areas– GBI has 7 regional labs; – Eastern Regional Lab is located in Augusta

and serves 15 counties

There is NO national system of forensic laboratories

So…

there is little organization and consistency among US forensic labs

Crime Lab Departments• Physical Science

– Chemistry (drug analysis) * – Trace Evidence (hair, fiber, soil, glass, paint, GSR)

• Biology (blood, DNA, cells) *• Firearms (ballistics, toolmarks) *• Questioned Documents (handwriting, documents,

impressions)

• Photography• Toxicology (drugs/alcohol/poisons in bio. samples) *• Fingerprints• Pathology (manner/cause of death)

Crime Lab Statistics

• State funded labs have a budget of ~$1 bil.• Average salary for an analyst is ~$50k/yr• ~90% of all analyses are for controlled

substance ID• ~20% of cases are backlogged (>30 days)

– most are DNA analyses• Oldest lab in world is in Lyons, France (1910)• Oldest lab in US is LAPD (1923)

Federal Forensics Labs

• Federal Bureau of Investigation– Largest in the world– Located in Quantico, VA– Operated by the Department of Justice (DOJ)

• Drug Enforcement Agency– Drug-related crimes– 21 regional divisions– Operated by the DOJ

Federal Forensics Labs

• Bureau of Alcohol, Tobacco, Firearms, and Explosives– Crimes involving alcohol, tobacco, firearms,

explosives, suspected arson, and organized crime

– National Laboratory Center located in Beltsville, MD

– Operated by the DOJ

Federal Forensics Labs

• United States Postal Inspection Service– Crimes involving the mail– Located in Dulles, VA– Operated by the United States Postal Service

• United States Fish & Wildlife Service– Crimes against wildlife– Located in Ashland, OR– Operated by the Department of the Interior

• Orfila (1814)– Father of forensic toxicology.– First treatise on detection of poisons and their effects on

animals.• Bertillon (1879)

– Father of criminal identification– Developed the science of anthropometry—the taking of

body measurements as a means of distinguishing people.

• Galton (1892)– First statistical proof supporting the uniqueness of

fingerprints.• Gross (1893)

– Father of criminalistics– First treatise describing the application of science to the

field of criminal investigation

Founding Scientists

• Locard (1910)– Father of forensic science. – Developed the idea of cross-transfer of evidence

• Osborn (1910)– Developed the fundamental principles of document

examination.• Lattes (1915)

– Developed a procedure to ID blood groups from dried bloodstains.

• Goddard (1925)– Refined the techniques of bullet ID with the

comparison microscope.• McCrone (1977)

– Perfected the use of the microscope in forensic investigation.

Methodology

• Locard’s Exchange Principle“Whenever two objects come into contact, there

is always a transfer of material. The methods of detection may not be sensitive enough to demonstrate this, or the decay rate may be so rapid that all of the evidence of transfer has vanished after a given time. Nonetheless, the transfer has taken place.”

Methodology

• The Scientific Method1. Observe a problem or questioned

evidence and collect objective data

2. Consider a hypothesis or possible solution to the problem based on observation.

• This step requires inductive reasoning (specific general), experience, and imagination.

Methodology

3. Examine, test, and analyze to support or refute the hypothesis.

4. Use deductive reasoning (general specific) to make a determination as to the significance of the evidence.

Methodology

5. Evaluate and verify all evidence.• This step is especially critical to a forensic

scientist because someone’s liberty can be at stake.

6. Develop a theory or opinion that is able to stand up to scientific and legal scrutiny.

Criminal Justice and the LawUS Constitution is the supreme body of laws

that trumps all• Statutory Law (legislation)

– Enacted by a governmental body or agency having the power to make laws (such as Congress)

• Common Law (case law)

– Made by judges– Precedents allow for consistency and

predictability in how the law is applied

• Civil Law (code law)

– Collection of codified statutes– Precedents are given less weight– Deals with relationships between individuals– More concerned with assigning blame than

with establishing intent– “Preponderance of evidence” is required to

convict

• Criminal Law (penal law)

– Body of rules that defines conduct prohibited by the state and assigns punishment for breach

– Punishments are related to the “guilty act” and the “guilty mind”

– Distinguished between “major” and “minor” crimes

– “Beyond a reasonable doubt” is required to convict

Steps in Pursuing Justice• Once a crime is committed and discovered…

– A suspect may be identified– Police investigate what may have happened– Information is collected– Crime scene is documented and searched for

evidence– Info is assembled into a report for the prosecutor– Investigation ensues– If enough evidence can establish probable

cause, then an arrest warrant is issued

• After a suspect has been arrested…–S/he is booked, fingerprinted,

photographed, and informed of his/her Miranda rights

–Brought before a judge within 48 hrs for arraignment to hear charges and enter a plea

• After a defendant’s plea is made…–A preliminary hearing is conducted

before a judge• This is to determine whether there is

enough evidence to proceed to a trial• Probable cause must be established

–Federal gov’t and some states may use a grand jury for felony cases• Defendant is not entitled to counsel

• Pleading “not guilty by reason of insanity”…–Requires the defendant to prove the

inability to “know right from wrong” at the time of the commission of the crime

– It removes the requirement to demonstrate intent

• A person is presumed innocent until proven guilty–The burden of proof rests with the

prosecution–Only 50% of all arrests lead to

conviction–Only 25% of all convictions are

sentenced to 1+ years in prison

• Plea bargaining can reduce the burden on the court by allowing a defendant to plead guilty to a lesser charge and avoid a trial– 90% of all cases are “pleaded down”

Types of Crimes

A broken law is called a violation.• INFRACTION “regulatory offenses”

– Least serious class of crime– Can be proceeded against without the right to

a jury trial and/or indictment– Punishable by fines– Include traffic tickets/violations, jaywalking,

littering, disturbing the peace

• MISDEMEANOR– More serious class of crime than infraction– Punishable by 1 year or less in prison, house-

arrest, probation, community service…– Include petty theft, prostitution, public

intoxication, disorderly conduct, trespassing…

• FELONY– Most serious class of crime– Punishable by more than 1 year in prison or

by death– Include aggravated assault/battery, arson,

burglary, grand theft, robbery, murder, rape…

Federal Rules of Evidence (1975)

• To be acceptable in court, evidence must be RELEVANT; that is, it should be both MATERIAL and PROBATIVE.– Material evidence has some logical

connection to a fact of consequence to the outcome of a case

– Probative evidence can prove or disprove legal elements of the case

• The forensic scientist, or expert witness, has an obligation to be an advocate for the truth, and should not take sides for either the defense or prosecution.

• The person who presents scientific evidence must establish credibility via credentials, background, and experience.

The Frye standard (Frye vs. US, 1923)

• Frye was convicted of murder. On appeal, defendant’s counsel offered an expert witness to testify to the result of a deception (pre-polygraph) test, claiming that during the first trial, the testimony was not accepted.

• SCOTUS let the conviction stand and stated that scientific evidence must have gained “general acceptance” to be accepted in court– At that time, the deception test was not “generally

accepted”…

The Frye standard

– Commonly called the “general acceptance” test

– Dictates that scientific evidence is admissible at trial only if the methodology or science is “generally accepted” in the field of study

– Only applies to new science/technologies

The Daubert standard (Daubert vs. Merrell Dow Pharmaceuticals, 1993)

• Daubert family sued Dow claiming that children’s birth defects had been caused by mother’s prescription drugs

• The trial court decided that evidence did not meet the Frye Standard

• In appeals, SCOTUS decided that the Frye Standard was no longer appropriate because of technological sophistication

The Daubert Ruling

– The judge is the “gatekeeper”– Applies to federal courts– Endorses the classical definition of the

Scientific Method• Hypothesis testing• Estimates of error rates• Peer-reviewed publication• General acceptance• Technique standardization