Forensics Essay, Research Paper
Forensics is defined as the aplication of science to interpret clues for crime investigation. The earliest forensic scientists were physicianswho were called upon to give an opinion as to the cause of death in individuals. Now most of the forensic scientists are investigators that pick up clues at the crim scene. Because criminals often are not the brightest people on the planet they often do not plan out a burglary or theft and carelessly leave behind distict clues that allow an invetigator to track them relatively easily. There are many areas of forensics which include: general crime scene investigation, forensic chemestry, forencic toxicology,forensic pathology, genetic figerprinting, fingerprinting and chromotography.
The purpose of crime scene investigation is to help establish what happened (crime scene
reconstruction) and to identify the responsible person. This is done by carefully documenting the conditions at a crime scene and recognizing all relevant physical evidence. The ability to recognize and collect the evidence is important in solving and prosecuting violent cases. In majority of the cases, The law enforcement officer who protects and searches the crime scene plays major part in determining whether the physical evidence will be used in solving or prosecuting the violent crime.
Crime scene investigation is not what we think it is, unlike the movies, is actually a difficult and time consuming job. There is no substitute for a careful and thoughtful approach. One should not leap into conclusions as to what happened based on what little information he has with him or her, but generate several theories of the crime, keeping the ones that have not been crossed out by incoming information at the scene. Reasonable inferences about what happened are produced from the scene and appearance and information from witnesses. These theories will help guide the investigator to document specific conditions and recognize valuable evidence.
Documenting crime scene conditions can include immediately recording transient detail such as lighting (on/off), drapes (open/closed), weather, or furniture moved by medical teams. Certain evidences such as shoe prints or gunshot residue is fragile and if not collected immediately can be destroyed or lost. The scope of the investigation also extends to considerations of arguments which might be generated in this case (self defense / suicide) and documenting conditions which would support or refute these arguments.
In addition, it is important to be able to recognize what should be present at a scene and what should not (victim’s vehicle/wallet) such as objects which appear out of place (ski mask) which might have been left by the assailant. It is also important to determine the full extent of a crime scene. A crime scene is not merely the immediate area where the body is located or where an assailant concentrated his activities but can also encompass a vehicle and access/escape routes.
Although there are common items which are frequently collected as (evidence fingerprints, shoe prints or bloodstains ), literally any object can be used as physical evidence. Anything which can be used to connect the victim to a suspect or a suspect to a victim or crime scene is relevant physical evidence. Using the “shopping list” approach (collecting all blood stains, hairs, or shoe prints in recognizing the best evidence. For example, collecting bloodstains under the victim’s body can be excellent physical since it can be directly tied to a matchbook found in a suspect’s pocket.
Since a weapon or burglar tool is easily recognized as significant physical, it is frequently destroyed by the perpetrator. Sometimes the only remaining evidence is microscopic evidence consisting of hair fibers, or other small traces the assailant unknowingly leaves behind or takes with him. Although this evidence is effectively collected when the clothing of the suspect or victim is taken, protocols (involving tape lifts ) should be in place to process nude bodies so as to not lose this fragile evidence.
Forensic chemistry is the application of chemistry to the investigation of a crime. The investigation of the crime is , however, is not limited to crime against individuals such as home suicidal, theft, fraud and arson. Forensic chemists also involved in the investigations of crime against society such as food adulteration, environmental pollution, use and pollution of unsafe chemicals and dangerous working conditions.
The application of chemistry to the study of physical or theoretical problems, the results of which may be entered into court as technical evidence. Boundaries are not sharply defined for forensic chemistry, and it includes topics that are not entirely chemical by nature.
Some of the items most often encountered in crime laboratories, and the information sought in regard of them , are: (1) Body fluids and viscera to be analysed for poisons, drugs or alcohol, quantitation of which may assist in determining the dosage taken or the person’s behavior prior to death; (2) Licit and licit pills, vegetable matter, and pipe residues for the presence of controlled substances; (3) Blood, saliva, and seminal stains, usually in dried form, to be checked for species, type and genetic data. (4) hairs to determine animal or human; if human, the race, body area of originated general characteristics; (5) Fibers, to determine type ( vegetable, animal, mineral or synthetic), composition, dyes used, and processing marks; (6)liquor, for alcoholic proof, trace alcohols, sugars, colourants, and other signs of adulteration; (7)paint, glass, plastics, and metals, usually in millimeter -sized chips, to classify and compare known materials; (9) Swabs from the hands of the suspects, to be checked for the presence of gunshot residue; (10) Debris from a fire or explosion scene, for the remains of the accelerant or explosive used.
Forensic Toxicology is an interdisciplinary science dealing with and interpretation of drugs and chemical samples for medical-legal purposes The hybrid and analytical chemistry, pharmacy toxicology. The Forensic Science Foundation said,”Forensic toxicology is the study and understanding of the harmful effects of external substances introduced into the living systems within a medical text. There are three major case load and forensic toxicology laboratories; drug abuse resulting from illegal use of drugs; paratoxicological aspects of criminal investigations on post mortem cases – analytical studies in the medical examiner to determine the case.In addition, many forensic toxicology laboratories assist local hospitals and physicians with diagnoses and patient care in emergency positions or with those patients requiring complex therapy. “The Society of Forensic Toxicology describes forensic toxicologists as scientist involving the analysis of tissue and body fluids for drugs and poisons, and who interpret the resulting information in the judiciary context. The forensic toxicologist as ascertain a chain of evidence or custody for each sample analysis, and documents the methodology and data collected, and is therefore prepared to defend the findings in legal hearings or trials. Along with the establishment of the New York City Medical Examination in 1990, the lst laboratory forensic laboratory was established. Other cities and counties have subsequently established similar systems. About thirty percent of medical-legal investigations are now performed by the medical examiners office rather than coroners office.
The most commonly encountered drugs and chemical involved in fatal poisoning include ethyl alcohol, barbiturates, carbon monoxide, morphine, proxyphene, and benzodiazepines.The role of ethyl alcohol in death is rarely due to its direct toxic effects but to its indirect role in accidents.
The circumstance of death in approximately twenty percent of the population require a thorough medical-legal investigation. The forensic toxicologist provides for the isolation of chemicals and subsequent analysis in an effort to determine if a chemical agent played a role in the cause of death. At autopsy the forensic pathologist collects postmortem specimens. The specimens are specially provided by the toxicologist for the subsequent analysis. The distribution of the chemicals in the body provides information about the mode of exposure(ingestion, injection, inhalation, and s on) and the time of exposure relative to death.
The forensic toxicologist has a number of isolation techniques (steam
distillation, selective solvent extraction, microdiffusion), depending on the tissue and the analyte,
which allow for the recovery of drugs and chemicals from biological samples. Once the substance for the analysis has been removed from the tissue specimen, the forensic toxicologist uses chromatography, spectrophotometry, and immunoassays to qualitatively and quantitatively to determine the drug.
The forensic toxicologist must then interpret the analytical data collected from the
analytical methods. Pharmaceutical manufacturers are one source of toxicology information relative to compounds that they have developed, manufactured, and marketed. The published literature provides the second source of toxicology data. The greatest challenge facing the forensic toxicologist is the interpretation of combinations of various drugs and chemicals and their complex interactions.
Another rather large part of foresic science is pathology. It is a large field including identifying the decedent, determining time of death, autopsies, and determining the cause of death. It requires a lot of patience and concentration to make sure you find every piece of evidence and clues to the death.
Identifying the decedent standardly incorporates physical description, scars and marks, fingerprints, photographs, Age, Dental features, Radiological evidence, blood factors, and medical indications.
Another way is through Genetic Fingerprints. The human body is composed of millions of microscopic cells. Each cell contains an unique code, the genetic code that determines what we look like and how we develop. The code takes the form of long strings of molecules called DNA. No two people have identical DNA unless they are identical twins.
The process of making DNA profile may begin with a scrape of stained clothing found at the scene of the crime. Atuft of hair or droplets of body fluids such as blood can be used too. The material is soaked so that any body cells in the stain come away from the cloth and into the liquid. The cells are then broken open to let out the long threads of DNA. These are treated chemically to cut them into tiny pieces. A block of these DNA fragments is then placed at one end to the other, the pieces of DNA move through the jelly in the direction of the electric currents. The process is called electrophoresis. The shorter pieces of DNA can move through the jelly more easily than the longer pieces. After a while, the DNA separates out into bands according to the size although at this stage the bands are invisible.
The pattern of the DNA bands then has to be transferred to a nylon sheet. The nylon sheet is then treated to make the DNA radioactive. When photographic film is laid on top of the nylon sheet for a while and then developed chemically, the bands of DNA appear as dark stripes of different thickness on the film. If the pattern of bands produced by cells found at the scene of the crime exactly matches the pattern made by cells collected from the suspect then the body cells from both samples must belong to the suspect and he or she must have been present at the scene of the crime. With a good sample, that is rich in DNA, the chance of two people producing the same genetic fingerprint is only one in 2.7 million, which is good enough for a court of law. However, people who are related do have similarities in their DNA. The chances of two related people producing the same genetic fingerprint is as high as 1 in 200. If there is not enough good quality DNA material for a reliable test, the chance of two people producing the same the genetic fingerprint could rise to 1 in 50. So the value of DNA profiling depends on the circumstances of the case.
Fingerprints are infallible means of identification. In addition to their value in the apprehension of criminals, fingerprints can ensure personal identification of humanitarian reasons, such as in cases of amnesia, missing persons, or unknown deceased. Fingerprints are invaluable in effecting identifications in tragedies such has fire, flood, and vehicle crashes. In criminal matters, besides establishing the identity of the arrested person, fingerprint records provide a history of known offenders, or indicate when a person is a offender. The vast majority of fingerprints maintained in the Identification Division of the Federal Bureau of Investigation of the United States, the largest repository of fingerprints in the world, are for civil records.
The latest fingerprint section of the Federal Bureau of Investigation deals with the identification of single or latent (hidden) fingerprints developed at the scene of a crime or upon articles of evidence. This generally involves the examination of fragmentary latent finger, palm or even foot developed by appropriate processes on objects associated with various crimes.
The traditional way of dusting surfaces for fingerprints is still used most of the time. In most cases it works very well, but sometimes different methods are needed. Forensic scientists can now use a small portable laser to look for fingerprints. The scientists “paints” the scene of crimes with the laser beam. As the laser beam sweeps across doors, walls and furniture, any fingerprints on them glow because they are fluorescent. Some atoms in the print absorb the laser light, and then release it again in a for of a burst of light. All of these tiny flashes combine to make
the whole print glow when the laser beam hits it. The technique of laser-sweeping enables large areas to be searched quickly, and prints in odd places can be found. Dusting the same surfaces with powder would take much longer and prints in unlikely places could be miss altogether. Prints found by a laser can also be dusted with fluorescent powder to make them show up even more clearly so they can be photographed.
Fibers play an important role in crime detection. A fiber found on a suspect may match fibers from clothings, carpets or upholstery at the scene of the crime. Or a fiber from the suspect’s clothing maybe found at the scene of the crime. Sample of fibers from the suspect and from the scene of the crime can be compared in many ways to see if they match. The samples may appear similar through the microscope when viewed under ordinary light conditions, but one sample may look quite different under ultraviolet light. Any dyes present in the fibers can be dissolved out and then separated by thin-layer chromatography.
In a simple form of chromatography, a solution of the dye is soaked up by a strip of absorbent paper. Different substances in the dye move along the paper at different rates, so they become separated into distinct bands of diffe- rent colors. If two samples of dye are identical, they will produce identical set of bands. If all of the above tests show the fibers to be similar, they are finally analyzed to make sure they are made of the same substance.
Analysis can also be used to find the source of fibers. For example, in one recent case, analysis of fibers revealed that they came from a single batch of a particular manufacturer’s space carpets. Automobiles fitted with the carpets were traced, and the criminal was found among the owners.
Like thin film chemography, gas chromatography is used to separate substances in mixtures, however, in this case, substances are in gaseous form. One of the most common applications of gas chromatography in forensic science is for the measurement of the alcohol content in the blood. This is carried out when a driver has failed a breath test, and is suspected of having drunk too much alcohol.
A stream of nitrogen gas is blown through a sample of the driver’s blood. The nitrogen removes alcohol from the blood, and carries it as a vapour through a long tube. This is packed with a material that holds back any other substances that have been removed from the body by the nitrogen. At the far end of the tube, any alcohol that emerges is detected and measured by an electronic device. As the original amount of blood in the sample is known, the concentration of alcohol that was in it can then be calculated. In recent years, gas chromatography has become one of the most important techniques in forensic science and has led to thousands of successful prosecutions.
FORENSIC SCIENCE TIMELINEBCE Evidence of fingerprints in early paintings and rock carvings of prehistoric humans
700s Chinese used fingerprints to establish identity of documents and clay sculpture, but without any formal classification system.
1000 Quintilian, an attorney in the Roman courts, showed that bloody palm prints were meant to frame a blind man of his mother’s murder.
1248 A Chinese book, Hsi Duan Yu (the washing away of wrongs), contains a description of how to distinguish drowning from strangulation. This was the first recorded application of medical knowledge to the solution of crime.
1609 The first treatise on systematic document examination was published by Fran?ois Demelle of France
1686 Marcello Malpighi, a professor of anatomy at the University of Bologna, noted fingerprint characteristics. However, he made no mention of their value as a tool for individual identification.
1784 In Lancaster, England, John Toms was convicted of murder on the basis of the torn edge of wad of newspaper in a pistol matching a remaining piece in his pocket. This was one of the first documented uses of physical matching.
1800s Thomas Bewick, an English naturalist, used engravings of his own fingerprints to identify books he published.
1810 Eugne Fran?ois Vidocq, in return for a suspension of arrest and a jail sentence, made a deal with the police to establish the first detective force, the S?ret? of Paris. The first recorded use of question document analysis occurred in Germany. A chemical test for a particular ink dye was applied to a document known as the Konigin Hanschritt.
1813 Mathiew Orfila, a Spaniard who became professor of medicinal/forensic chemistry at University of Paris, published Traite des Poisons Tires des Regnes Mineral, Vegetal et Animal, ou Toxicologie General l. Orfila is considered the father of modern toxicology. He also made significant contributions to the development of tests for the presence of blood in a forensic context and is credited as the first to attempt the use of a microscope in the assessment of blood and semen stains.
1823 John Evangelist Purkinji, a professorprofessor of anatomy at the University of Breslau, Czecheslovakia, published the first paper on the nature of fingerprints and suggested a classification system based on nine major types. However, he failed to recognize their individualizing potential.
1828 William Nichol invented the polarizing light microscope.
1830s Adolphe Quetelet, a Belgian statistician, provided the foundation for Bertillon’s work by stating his belief that no two human bodies were exactly alike.
1831 Leuchs first noted amylase activity in human saliva.
1835 Henry Goddard, one of Scotland Yard’s original Bow Street Runners, first used bullet comparison to catch a murderer. His comparison was based on a visible flaw in the bullet which was traced back to a mold.
James Marsh, an Scottish chemist, was the first to use toxicology (arsenic detection) in a jury trial.
H. Bayard published the first reliable procedures for the microscopic detection of sperm. He also noted the
different microscopic characteristics of various different substrate fabrics.
Jean Servais Stas, a chemistry professorprofessor from Brussels, Belgium, was the first successfully to identify
vegetable poisons in body tissue.
Ludwig Teichmann, in Kracow, Poland, developed the first microscopic crystal test for hemoglobin using
An English physician, Maddox, developed dry plate photography, eclipsing M. Daguerre’s wet plate on tin
method. This made practical the photographing of inmates for prison records.
Sir William Herschel, a British officer working for the Indian Civil service, began to use thumbprints on
documents both as a substitute for written signatures for illiterates and to verify document signatures.
The Dutch scientist J. (Izaak) Van Deen developed a presumptive test for blood using guaiac, a West Indian
The German scientist Sch?nbein first discovered the ability of hemoglobin to oxidize hydrogen peroxide making
it foam. This resulted in first presumptive test for blood.
Odelbrecht first advocated the use of photography for the identification of criminals and the documentation of
evidence and crime scenes.
Thomas Taylor, microscopist to U.S. Department of Agriculture suggested that markings of the palms of the
hands and the tips of the fingers could be used for identification in criminal cases. Although reported in the
American Journal of Microscopy and Popular Science and Scientific American, the idea was apparently never
pursued from this source.
Rudolph Virchow, a German pathologist, was one of the first to both study hair and recognize its limitations.
Henry Faulds, a Scottish physician working in Tokyo, published a paper in the journal Nature suggesting that
fingerprints at the scene of a crime could identify the offender. In one of the first recorded uses of fingerprints
to solve a crime, Faulds used fingerprints to eliminate an innocent suspect and indicate a perpetrator in a
Gilbert Thompson, a railroad builder with the U.S Geological Survey in New Mexico, put his own thumbprint
on wage chits to safeguard himself from forgeries.
Alphonse Bertillon, a French police employee, identified the first recidivist based on his invention of
Arthur Conan Doyle published the first Sherlock Holmes story in Beeton’s Christmas Annual of London.
Alexandre Lacassagne, professorprofessor of forensic medicine at the University of Lyons, France, was the
first to try to individualize bullets to a gun barrel. His comparisons at the time were based simply on the number
of lands and grooves.
Hans Gross, examining magistrate and professor of criminal law at the University of Graz, Austria, published
Criminal Investigation, the first comprehensive description of uses of physical evidence in solving crime. Gross
is also sometimes credited with coining the word criminalistics.
(Sir) Francis Galton published Fingerprints, the first comprehensive book on the nature of fingerprints and their
use in solving crime.
Juan Vucetich, an Argentinean police researcher, developed the fingerprint classification system that would
come to be used in Latin America. After Vucetich implicated a mother in the murder of her own children using
her bloody fingerprints, Argentina was the first country to replace anthropometry with fingerprints.
Alfred Dreyfus of France was convicted of treason based on a mistaken handwriting identification by Bertillon.
Sir Edward Richard Henry developed the print classification system that would come to be used in Europe and
North America. He published Classification and Uses of Finger Prints.
Paul Jesrich, a forensic chemist working in Berlin, Germany, took photomicrographs of two bullets to
compare, and subsequently individualize, the minutiae.
Paul Uhlenhuth, a German immunologist, developed the precipiten test for species. He was also one of the first
to institute standards, controls, and QA/QC procedures. Wassermann (famous for developing a test for
syphilis) and Sch?tze independently discovered and published the precipiten test, but never received due
Karl Landsteiner first discovered human blood groups and was awarded the Nobel prize for his work in 1930.
Max Richter adapted the technique to type stains. This is one of the first instances of performing validation
experiments specifically to adapt a method for forensic science. Landsteiner’s continued work on the detection
of blood, its species, and its type formed the basis of practically all subsequent work.
Sir Edward Richard Henry was appointed head of Scotland Yard and forced the adoption of fingerprint
identification to replace anthropometry.
Henry P. DeForrest pioneered the first systematic use of fingerprints in the United States by the New York
Civil Service Commission.
professor R.A. Reiss, professor at the University of Lausanne, Switzerland, and a pupil of Bertillon, set up one
of the first academic curricula in forensic science. His forensic photography department grew into Lausanne
Institute of Police Science.
The New York State Prison system began the first systematic use of fingerprints in United States for criminal
At Leavenworth State Prison, Kansas, Will West, a new inmate, was differentiated from resident convict Will
West by fingerprints, not anthropometry. They were later found to be identical twins.
Oskar and Rudolf Adler developed a presumptive test for blood based on benzidine, a new chemical
developed by Merk.
American President Theodore Roosevelt established Federal Bureau of Investigation (FBI).
Victor Balthazard, professor of forensic medicine at the Sorbonne, with Marcelle Lambert, published the first
comprehensive hair study, Le poil de l’homme et des animaux. In one of the first cases involving hairs, Rosella
Rousseau was convinced to confess to murder of Germaine Bichon. Balthazard also used photographic
enlargements of bullets and cartridge cases to determining weapon type and was among the first to attempt to
individualize a bullet to a weapon.
Edmund Locard, successor to Lacassagne as professor of forensic medicine at the University of Lyons,
France, established the first police crime laboratory.
Albert S. Osborne, an American and arguably the most influential document examiner, published Questioned
Masaeo Takayama developed another microscopic crystal test for hemoglobin using hemochromogen crystals.
Victor Balthazard, professor of forensic medicine at the Sorbonne, published the first article on individualizing
Leone Lattes, professor at the Institute of Forensic Medicine in Turin Italy, developed the first antibody test for
ABO blood groups. He first used the test in casework to resolve a marital dispute. He published L’Individualit?
del sangue nella biologia, nella clinica, nella medicina, legale, the first book dealing not only with clinical issues,
but heritability, paternity, and typing of dried stains.
International Association for Criminal Identification, (to become The International Association of Identification
(IAI), was organized in Oakland, California.
Albert Schneider of Berkeley, California first used a vacuum apparatus to collect trace evidence.
Edmond Locard first suggested 12 matching points as a positive fingerprint identification.
Locard published L’enquete criminelle et les methodes scientifique, in which appears a passage that may have
given rise to the forensic precept that “Every contact leaves a trace.”
Charles E. Waite was the first to catalog manufacturing data about weapons.
Georg Popp pioneered the use of botanical identification in forensic work.
Luke May, one of the first American criminalists, pioneered striation analysis in tool mark comparison,
including an attempt at statistical validation. In 1930 he published The identification of knives, tools and
instruments, a positive science, in The American Journal of Police Science.
Calvin Goddard, with Charles Waite, Phillip O. Gravelle, and John H Fisher, perfected the comparison
microscope for use in bullet comparison.
John Larson and Leonard Keeler designed the portable polygraph.
Vittorio Siracusa, working at the Inst