An Introduction toForensic Science

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.

Forensic Science isApplied ScienceOften called criminalistics

Forensic Science appliesChemistryBiologyPhysicsGeology

Places physical evidence into a professional discipline.to civil and criminal law}

The development ofForensic Science

Sir Arthur Conan DoylePopularized physical detection methods in a crime sceneDeveloped the character Sherlock Holmes

Sir Arthur Conan Doyle1887 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." had a considerable influence on popularizing scientific crime-detection methods

Mathieu Orfila (1787 1853)Father of Forensic Toxicology

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

Alphonse Bertillon (1853 1914)Father of Criminal DetectionDevised the first scientific system of personal identification, using body measurements known as anthropometry in 1879.

Francis Galton (1822 1911)Conducted the first definitive study of fingerprints and their classification.

1892 Treatise entitled Finger Prints

Leone Lattes (1887 1954)Devised a simple procedure for determining the blood type (A,B,O,AB) of a dried bloodstain

Calvin Goddard (1891 1955)Used a comparison microscope to determine if a bullet was fired from a specific gunPublished study of tool marks on bullets

Albert S. Osborn (1858 1946)Developed fundamental principles of document examination1910 Treatise Questioned Documents

Was responsible for the acceptance of documents as scientific evidence by the courts

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.

Organization of aCrime Laboratory

Crime LabsSince 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 (1990s)Presently there are 350 Crime Laboratories in the U.S.

Services of the Crime LabMany local crime laboratories have been created solely for the purpose of processing evidenceCurrently 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.

Crime Lab UnitsStandardPhysical ScienceBiologyFirearmsDocumentsPhotographyOptionalToxicologyFingerprintsPolygraphVoice PrintEvidence

Basic Services Provided byFull-Service Crime Laboratories Physical Science Unit: Applies the principles and techniques of ChemistryPhysicsGeologyto the identification and comparison of crime-scene evidenceBiology Unit: Identifies dried bloodstains and body fluidsCompares hairs and fibersIdentifes and compares botanical materials such as wood and plantsPerforms DNA analysis

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' locations

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 scientist

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 service

The Functions of theForensic Scientist Analysis of Physical EvidenceThe 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.

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.

Other Forensic ServicesDeath 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 autopsy

Other Forensic Services - 2Forensic 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 Mortiswhen 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 Mortisthe 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.

Other Forensic Services - 3Forensic 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.

Other Forensic Services - 4Forensic EntomologyThe 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

Other Forensic Services - 5Forensic PsychiatryThe 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.

Other Forensic Services - 6Forensic OdontologyAn 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 explosions

Forensic AnalysisCan include organic and inorganic analytical techniquesOrganic 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.

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