An Introduction to Forensic Science - PowerPoint Presentation

Slide1

An Introduction toForensic ScienceSlide2

What is Forensic Science?

…the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system.Slide3

Forensic Science is…

Applied ScienceOften called “criminalistics”Slide4

Forensic Science applies

ChemistryBiology

PhysicsGeologyPlaces physical evidence into a professional discipline.

to civil and criminal law

}Slide5

The development ofForensic ScienceSlide6

Sir Arthur Conan Doyle

Popularized physical detection methods in a crime scene

Developed the character Sherlock HolmesSlide7

Sir Arthur Conan Doyle

1887 published first novel, A Study in Scarlet

"I've found it! I've found it," he shouted to my companion, running towards us with a test-tube in his hand. "I have found a re-agent which is precipitated by haemoglobin, and by nothing else . . . . Why, man, it is the most practical medico-legal discovery for years. Don't you see that it gives us an infallible test for blood stains? . . . . The old guaiacum test was very clumsy and uncertain. So is the microscopic examination for blood corpuscles. The latter is valueless if the stains are a few hours old. Now, this appears to act as well whether the blood is old or new. Had this test been invented, there are hundreds of men now walking the earth who would long ago have paid the penalty of their crimes. . . . Criminal cases are continually hinging upon that one point. A man is suspected of a crime months perhaps after it has been committed. His linen or clothes are examined and brownish stains discovered upon them. Are they blood stains, or mud stains, or rust stains, or fruit stains, or what are they? That is a question which has puzzled many an expert, and why? Because there was no reliable test. Now we have the Sherlock Holmes's test, and there will no longer be any difficulty."

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had a considerable influence on popularizing scientific crime-detection methods Slide8

Mathieu Orfila (1787 – 1853)

Father of Forensic Toxicology

1814 - Treatise on detection of poisons & their effects on animals.Slide9

Alphonse Bertillon (1853 – 1914)

Father of Criminal DetectionDevised the first scientific system of personal identification, using body measurements known as

anthropometry in 1879. Slide10

Francis Galton (1822 – 1911)

Conducted the first definitive study of fingerprints and their classification.

1892 – Treatise entitled Finger PrintsSlide11

Leone Lattes (1887 – 1954)

Devised a simple procedure for determining the blood type (A,B,O,AB) of a dried bloodstain Slide12

Calvin Goddard (1891 – 1955)

Used a comparison microscope to determine if a bullet was fired from a specific gun

Published study of “tool marks” on bulletsSlide13

Albert S. Osborn (1858 – 1946)

Developed fundamental principles of document examination

1910 – Treatise Questioned DocumentsWas responsible for the acceptance of documents as scientific evidence by the courtsSlide14

Edmond Locard (1877 – 1966)

Demonstrated how the principles developed by Hans Gross could be incorporated into a workable crime lab.

Locard's exchange principle states that once contact is made between two surfaces a transfer of material(s) will occur. Slide15

Organization of aCrime LaboratorySlide16

Crime Labs

Since the 1960's the number of crime labs increased due to the courts demanding secure scientifically evaluated evidence.

More crimeMore drug related crimeGreater need for physical evidenceUse of DNA profiling (1990’s)

Presently there are 350 Crime Laboratories in the U.S.Slide17

Services of the Crime Lab

Many local crime laboratories have been created solely for the purpose of processing evidence

Currently most of their energy and funds are used to analyze drugs and DNA. In 1932, Hoover first established a national forensics laboratory to support all law enforcement in the U.S.The oldest American forensics laboratory is in Los Angeles, California, created in 1923 by August Volmer. Slide18

Crime Lab Units

Standard

Physical ScienceBiologyFirearmsDocumentsPhotography

Optional

Toxicology

Fingerprints

Polygraph

Voice Print

EvidenceSlide19

Basic Services Provided byFull-Service Crime Laboratories

Physical Science Unit: Applies the principles and techniques of Chemistry Physics Geology

to the identification and comparison of crime-scene evidence

Biology Unit:

Identifies dried bloodstains and body fluids

Compares hairs and fibers

Identifes and compares botanical materials such as wood and plants

Performs DNA analysis

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Basic Services (continued)

Firearms Unit:

examinesFirearmsDischarged bulletsCartridge casesShotgun shellsAmmunition of all types

Document Examination Unit:

Analyzes handwriting, paper and printers of documents

Photography Unit:

Examines and records physical evidence at the crime scene and at suspects' locationsSlide21

Optional Services Provided by Full-Service Crime Labs

Toxicology Unit:

Examines body fluids and organs in order to determine the presence and identification of drugs and poisons Latent Fingerprint Unit:Processes and examines evidence for latent fingerprints i.e. those found on surfaces

Polygraph Unit:

Uses lie detectors, an essential tool of the crime investigator rather than the forensic scientistSlide22

Optional Services (continued)

Voiceprint Analysis Unit:

Involved in cases of telephone threats or tape-recorded messagesInvestigators may be able to connect a voice to a particular suspectEvidence-Collection Unit: Incorporates evidence collection into a total forensic science serviceSlide23

The Functions of theForensic Scientist

Analysis of Physical Evidence

The forensic scientist must be skilled in applying the principles and techniques of the physical and natural sciences in order to identify the many types of evidence that may be recovered during crime investigations. Expert witnessAn expert witness possesses a particular skill or has knowledge in a trade or profession that will aid the court in determining the truth. Slide24

The Functions of theForensic Scientist

(continued)

Specially trained evidence collection technicians

Training in Proper Recognition,

Collection, and Preservation of

Evidence is required so that

the forensic pathologist, as the

medical examiner or coroner,

can determine the cause of

death via an autopsy. Slide25

Other Forensic Services

Death can be classified into five different categories: natural death, homicide, suicide, accident or undetermined manner of death.

Forensic PathologyThe cause of death can often be determined by performing an autopsySlide26

Other Forensic Services - 2

Forensic Pathology

– continuedAfter a human body expires there are several stages of deathRigor Mortisimmediately following death, the muscles relax and then become rigid, shortening of the muscles.

Livor Mortis

when the human heart stops pumping, due to the blood begins to settle in the parts of the body closest to the ground due to gravity. The skin will appear dark blue or purple in these lower areas close to the ground.

Algor Mortis

t

he process in which the body temperature continually cools after death until it reaches room temperature, enabling the medical examiner to establish the general time of death. Slide27

Other Forensic Services - 3

Forensic Anthropology:

Primarily involves the identification and examination of skeletal remains, in order to determine if the remains are human or another type of animal.If human, ethnicity, sex, approximate age, and manner of death can often be determined by an anthropologist. Slide28

Other Forensic Services - 4

Forensic Entomology

The study of insects and their developmental stagesCan help to determine the time of death by knowing when those stages normally appear in the insect's life cycle Slide29

Other Forensic Services - 5

Forensic Psychiatry

The study of human behavior and legal proceedings in both civil and criminal casesIn civil and criminal cases, competency often needs to be determinedIn criminal trials, the evaluation of behavior disorders is often required in order to establish the psychological profile of a suspect. Slide30

Other Forensic Services - 6

Forensic Odontology

An odontologist can match bite marks to a suspect's teeth, or match a victim to his dental x-raysResults in an identification of an unknown individualForensic EngineeringUsed to analyze construction accidents, and the causes and origins of fires or explosionsSlide31

Forensic Analysis

Can include organic and inorganic analytical techniques

Organic analysis of unknown substances Includes analytical techniques such as Chromatography, UV- visible and infrared Spectrophotometry and Mass Spectrometry. Inorganic analysis Includes techniques such as the emission spectrum of elements, Atomic Absorption Spectrophotometry, Neutron Activation Analysis, and X-Ray Diffraction Analysis.