Introduction and Overview of Forensics Notes

These notes are based on the textbook "Criminalistics: An Introduction to Forensic Science" seventh edition by Richard Saperstein (ed. Prentice Hall, 2001 pp. 1-22)

Chapter 1

1. Introduction: Definition and Scope
   Forensic Science is the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system. The focus of Forensic Science is the Crime Lab using the principles and techniques of Biology, Chemistry, Physics, Geology, Anthropology and other sciences in order to place physical evidence into a professional discipline.
2. History and Development of Forensic Science
   Many believe Sir Arthur Conan Doyle had a considerable influence on popularizing scientific crime-detection methods through his fictional character, Sherlock Holmes. Read the quote from "A Study in Scarlet" 1887 on p.3 of "Criminalistics" by Richard Saperstein.

   "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."
   
   

   1. Mathieu Orfila: Is considered the father of forensic toxicology. He wrote first treatise on poisons and their effects in 1814.
   2. Aphonse Bertillon: devised the first scientific system of personal identification, using body measurements known as anthropometry.
   3. Francis Galton: undertook the first definitive study of fingerprints and developed a method of classifying fingerprints.
   4. Leone Lattes: devised a simple procedure for determining the blood type (A,B,O,AB) of a dried bloodstain.
   5. Calvin Goddard: was the first to use a comparison microscope to determine if a bullet was fired from a specific gun.
   6. Albert S. Osborn: developed fundamental principles of document analysis and was responsible for the acceptance of documents as scientific evidence by the courts.
   7. Hans Gross: described the application of scientific disciplines to the field of criminal investigation. He introduced the first forensic journal, "Kriminologie". He described how forensics would be assisted by the fields of microscopy, chemistry, physics, mineralogy, zoology, botany, anthropometry and fingerprinting.
   8. Edmond Locard: 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. Locard founded and directed the Institute of Criminalistics in Lyons, France.

3. Organization of a Crime Laboratory
   Crime laboratories have been organized by agencies that foresaw their potential application to criminal investigation. Since the 1960's the number of crime labs increased due to the courts demanding secure scientifically evaluated evidence.
   
   
   1. Services of the Crime Laboratory
      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.
   2. Basic Services Provided by Full-Service Crime Laboratories
      
      1. Physical Science Unit: applies the principles and techniques of chemistry, physics and geology to the identification and comparison of crime-scene evidence.
      2. Biology Unit: identifies dried bloodstains and body fluids, compares hairs and fibers, identifes and compares botanical materials such as wood and plants, and performs DNA analysis.
      3. Firearms Unit: examines firearms, discharged bullets, cartridge cases, shotgun shells, and ammunition of all types.
      4. Document Examination Unit: analyzes handwriting, paper and printers of documents.
      5. Photography Unit: examines and records physical evidence at the crime scene and at suspects' locations.
   3. Optional Services Provided by Full-Service Crime Labs
      
      1. Toxicology Unit: examines body fluids and organs in order to determine the presence and identification of drugs and poisons.
      2. Latent Fingerprint Unit: processes and examines evidence for latent fingerprints i.e. those found on surfaces.
      3. Polygraph Unit: uses lie detectors, an essential tool of the crime investigator rather than the forensic scientist.
      4. Voiceprint Analysis Unit: are involved in cases of telephone threats or tape-recorded messages. Investigators may be able to connect a voice to a particular suspect.
      5. Evidence-Collection Unit: incorporates evidence collection into a total forensic science service.
   4. The Functions of The Forensic Scientist
      
      1. 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. The "Frye versus U.S." court case established that a scientific technique must be "generally accepted" by the scientific community. (p.12, "Criminalistics" Saperstein Latent Fingerprint Unit: processes and examines evidence for latent fingerprints i.e. those found on surfaces.
      2. Expert witness: An expert witness possesses a particular skill or has knowledge in a trade or profession that will aid the court in determining the truth.
      3. 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.
   5. Other Forensic Science Services
      Death can be classified into five different categories: natural death, homicide, suicide, accident or undetermined manner of death.
      
      1. Forensic Pathology: The cause of death can often be determined by performing an autopsy.
         
         
         1. Rigor mortis: immediately following death, the muscles relax and then become rigid, shortening of the muscles.
         2. 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.
         3. Algor mortis: the 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.
      2. 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.
      3. Forensic Entomology: is the study of insects and their developmental stages, which can help to determine the time of death by knowing when those stages normally appear in the insect's life cycle.
      4. Forensic Psychiatry: is the study of human behavior and legal proceedings in both civil and criminal cases. In civil and criminal cases, competency often needs to be determined. In criminal trials, the evaluation of behavior disorders is often required in order to establish the psychological profile of a suspect.
      5. Forensic Odontology: An odontologist can match bite marks to a suspect's teeth, or match a victim to his dental x-rays, resulting in an identification of an unknown individual.
      6. Forensic Engineering: is used to analyze construction accidents, and the causes and origins of fires or explosions.
   6. Forensic Analysis also can include organic and inorganic analytical techniques.
      
      1. Organic analysis of unknown substances includes analytical techniques such as Chromatography, UV- visible and infrared Spectrophotometry and Mass Spectrometry. Chromatography is a means of separating and identifying organic components. Chromatography is especially useful in mixture separation i.e. many illicit drugs contain different materials which dilute the drug. Gas Chromatography separates molecules using a high temperature system to vaporize all the components which are subsequently separated on a column. Combining gas chromatography with mass spectrometry is currently one of the most accurate methods used to identify of an unknown substance.
      2. Inorganic analysis includes techniques such as the emission spectrum of elements, Atomic Absorption Spectrophotometry, Neutron Activation Analysis, and X-Ray Diffraction Analysis.

References:
Saperstein, Richard, "Criminalistics: An Introduction to Forensic Science," pp. 1-22. Prentice Hall, Inc., Upper Saddle, NJ 07458, 2001. ISBN 0-13-013827-4 (textbook with lots of background information and figures)