Analysis and Interpretation of Fire Scene Evidence (Forensic Science Techniques)
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Only its interpretation can err. Only human failure to find it, study and understand it, can diminish its value. Test firing of a weapon in the Firearms Section of a forensic lab. Criminalists analyze, compare, identify, and interpret physical evidence, then report results for use in the justice system. The main role of the criminalist is to objectively apply standard, scientific processing techniques of the physical and natural sciences to examine physical evidence. Physical evidence may be anything. It may be as subtle as a whiff of a flammable gas at an arson scene or as obvious as a pool of blood at a homicide scene.
The enormous range of material challenges the ingenuity of the criminalist who examines and identifies hair, fibers, blood, seminal and other body fluid stains, drugs, paint, glass, botanicals, soil, flammables and safe insulating material; restores obliterated, smeared or smudged markings; and identifies firearms and compares fired bullets, tool markings, and footwear impressions. In most cases, the amount of the evidence to be tested is very small, such as a drop of blood, a hair, or a piece of glass, but can be a vehicle or other large object. Using specialized training, analytical skill, and practical experience, the criminalist separates evidence from items having little or no value.
Next, the criminalist sorts, compares, and identifies the evidence, using chemical tests and instruments to develop useful information for investigation or at trial. These types of analyses are rarely routine; they require an eye for detail, a broad practical scientific background, and the ability to apply these skills in the laboratory. Perhaps the most important task of the criminalist lies in interpreting the results of the tests to help determine the facts.
Reconstructing the events of a crime can be very difficult. It requires an understanding of the meaning of results from the analysis of physical evidence, of the physical laws and processes involved, and the recognition of how they interact. Finally, any results and conclusions made by the criminalist must be conveyed to the others in the criminal justice system, such as officers, attorneys, and jurors.
This is done by written reports and expert testimony. The criminalist must express conclusions so that technical details are understood by the non-scientist jury, attorneys, and judges. Criminalists must be able to think critically and use scientifically valid methods to analyze anything and everything submitted to the laboratory.
They must be familiar with many different types of equipment and techniques in order to conduct the necessary testing. Many colleges and universities offer degrees and courses in forensic science. Accredited programs offer the necessary amount of science and math required to be a criminalist.
In deciding whether to get a degree in chemistry, biology, or forensic science, study the courses offered. At least 24 semester hours of either chemistry or biology is required and math is a must. Knowledge of statistics is becoming increasingly important. The title of the degree is not as important as the courses taken.
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The education of a criminalist never stops. Because forensic science is an ever-evolving field, criminalists must continually increase their knowledge in their discipline. To keep up with the many advances in science, the criminalist must take continuing education courses. After successfully completing an examination, the criminalist may become certified by the American Board of Criminalistics www. Entire forensic laboratories may prove their competence by becoming accredited to the International Organization for Standardization ISO standards.risserebelki.tk
Analysis and Interpretation of Fire Scene Evidence (Forensic Science Techniques)
ISO accreditation demonstrates best management practices coupled with the best science practices with the competency of the scientific staff. Currently, there are four U. Forensic laboratory accreditation is required by law in a number of states. Scientist preparing swabs for DNA testing. Scientist examining a sheet for biological and trace evidence. Criminalists assist the United States Department of Justice in helping other countries create or update forensic science services. There are many opportunities to teach at community colleges and universities training future criminalists.
As forensic science advances, more criminalists will be needed to perform new tests in an ever-expanding field of evidence. A criminalist specializing in DNA must have a solid scientific foundation and be flexible and willing to routinely implement newly-validated testing reagents, customized laboratory consumables, enhanced automation and instrumentation methods, and new DNA genetic markers. Interpretation of DNA evidence is one of the most challenging aspects of forensic DNA analysis especially as it relates to statistical calculations for DNA profile rarity and new software programs are constantly improving this task.
DNA analysis may be conducted in government and private DNA laboratories, criminal booking agencies, mass disaster sites, and international areas of conflict.
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Another progressive technology is Next Generation Sequencing NGS in which massive amounts of genetic information are obtained through the rapid synthesis of target DNA achieving greater statistical reporting power. Drug chemistry is one of the many forensic disciplines in a typical forensic laboratory. The drug chemist uses a wide variety of techniques and methods including color and microcrystal tests, chromatography thin layer, gas, liquid, and high-pressure liquid , spectrophotometry ultraviolet, visible, infrared, raman , spectrometry mass spectrometry , X-ray spectroscopy X-ray diffraction , and nuclear magnetic resonance spectroscopy.
Many of these tests are considered preliminary in nature as they do not identify a specific compound but a general class of compounds. Techniques that are considered confirmatory are those which actually determine the structure of a compound and thus identify a specific compound instead of a class of compounds. The drug chemist may have large quantities of drug materials to analyze or just milligrams of a material. The drugs may be pure or mixed with other substances which then require the chemist to extract the drugs for analysis. Drug analysis normally has the highest number of analyses in forensic laboratories due to the high incidence of drug abuse around the world.
In fire debris analysis, it is necessary to know how flammable liquids are made and how they burn in order to recognize both the flammable liquids and their breakdown products i. This cabin exploded because of a leak in a poorly installed propane gas line. Accumulated gas was set off by a loose electrical connection at the furnace.
Criminalists often combine multiple skills or work with other disciplines. Determining the cause of the explosion that destroyed this log cabin required collaboration among chemists, metallurgists, and engineers.
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Determining the origin where the fire started is not as easy as it was once thought. Several high-profile cases of wrongful conviction have made it clear that there is a need for more scientists with knowledge of chemistry and physics to enter the field.
Trace evidence testing covers a wide area of materials to be analyzed such as explosives, gunshot residue, hairs, and fibers. In many cases, criminalists must understand the physics of how evidence is produced. Criminalists must not only understand the composition of trace evidence but also understand the dynamics that create or alter physical evidence.
For example when an explosion occurs, it is very rare that the explosive or device that explodes is completely consumed or destroyed. Rather, they are transformed into residues and very small pieces. It is up to the criminalist to analyze these residues and recognize these small pieces for what they are i. The major difference between criminal forensic science and wildlife forensic science is that the victim and occasionally the suspect is an animal. The identification of wildlife evidence can be complicated because wildlife enforcement officers rarely seize whole animals which can be readily identified by a museum or zoo expert.
More typically parts or the products created from wildlife will be recovered as evidence. The characteristics which define an animal species are rarely present in those parts or products. Wildlife forensic scientists are often required to develop new ways to identify species through research with carefully documented known specimens before they can examine evidence in a case and testify in court.
An additional complication is that, while human forensics deals with only a single species homo sapiens , wildlife forensic scientists must be prepared to identify evidence from any species in the world that is illegally killed, smuggled, poached, or sold through an illicit market. While it might seem that wildlife forensic scientists face an overwhelming task in developing new and reliable ID techniques, they do have one advantage over other forensic scientists: sample size is rarely a problem.
Example seizures of wildlife evidence have included 20, pounds of suspected sea turtle meat, 10, pounds of ivory, and , suspected rhinoceros horn pills. Fisher, Barry A. Inman, K.
List of Forensics Techniques | Sciencing
Lentini, J. Mozayani, A. Saferstein R. Ubelaker, Douglas H. Digital data are all around us and are collected routinely in most investigations. Digital evidence examinations require very specific hardware and software tools to find numerous types of digital evidence. Examiners, depending upon their specialties, may discover evidence and provide testimony concerning the following:.
Computer forensics used to involve simply looking at individual computers which may have some connection to criminal activity. With the ready availability of access to the Internet, intrusions to gain access to or corrupt information on other computer systems by criminals have become widespread.
Network forensics is required to properly investigate and determine what happened. This extends to mobile devices with the explosion in smart phone and tablet systems that provide fully networked computing technology in the palm of your hand. The analysis of audio recordings requires techniques and procedures which continue to be evolving areas of research. Forensic speaker comparison, acoustic analysis and enhancement, and audio authenticity examinations are all important activities which can aid investigations and assist in the settlement of disputes. With capabilities to disguise voices as well as easily manipulate digital audio with off-the-shelf technology, the investigation of underlying acoustic patterns has become one of many important areas of both technological and linguistic research.
The advent of digital photography provides the potential to aid in the documentation of crime scenes and injuries. Digital photography also provides a source of images from witnesses, victims, and subjects due to the widespread availability of digital cameras in laptops, tablets, and smart phones.