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.