User:Sanniv bhaduri/Forensic science complete package

Introduction

Forensic science (often shortened to forensics) is the application of a broad spectrum of science to answer questions of interest to a legal system. This may be in relation to a crime or a civil action. The word forensic comes from the Latin adjective forensis, meaning "of or before the forum." In Roman times, a criminal charge meant presenting the case before a group of public individuals in the forum. Both the person accused of the crime and the accuser would give speeches based on their side of the story. The individual with the best argument and delivery would determine the outcome of the case. The use of the term "forensics" in place of "forensic science" is actually a globally-accepted misnomer considering that the term "forensic" is effectually a synonym for "legal" or "pertaining to courts", from the root Latin meaning. Because it is now so closely associated with the criminal scientific field, many dictionaries equate the word "forensics" with "forensic science."

Fields of application

Forensic science extends into a broad range of sub-sciences which utilize natural science techniques to obtain relevant criminal and legal evidence. Forensic science specialties include: •	Forensic Accounting – The acquisition, interpretation and study and of accounting evidence. •	Digital Forensics (also known as Computing Forensics) – The retrieval, reconstruction and interpretation of digital media (i.e. images, PDF's, e-mail messages, etc.) stored on a computer, for use as evidence. •	Forensic Document Examination – The reconstruction, study and interpretation of physical document-related evidence, such as handwriting analysis and printmaking. •	Forensic Economics – The acquisition, study and interpretation of evidence related to economic damage, which includes determination of lost benefits and earnings, business value and profit loss, lost household service value, labor replacement and future medical expense costs, etc. •	Forensic Engineering – The reconstruction, study and interpretation of structural or mechanical failure or in devices, buildings, etc. •	Forensic Linguistics – The study and interpretation of language for use as legal evidence. •	Forensic Photography – The art-science of reconstructing, interpreting and producing an accurate photographic reproduction of a crime scene for a court's benefit. •	Forensic Psychology and Psychiatry – The study, evaluation and identification of mentally-related illnesses and human behavior for the purpose of obtaining legal evidence. •	Forensic Anthropology is the practice of physical anthropology, as applied to a legal situation- typically the identification and recovery of skeletonized human remains (bones). •	Criminalistics is the application of combination of impression evidence (i.e. fingerprints, impressions left by footwear and tire tracks), trace evidence, controlled substances. •	Criminalistics includes evidence collected from a wide range of sciences to determine the answers of questions relating to the examination and comparison of criminal investigations. This evidence is typically processed in a crime lab. •	Forensic Biology includes performing DNA and serological analysis of bodily (physiological) fluids for the purpose of individualization and identification. •	Forensic Entomology assists in determining time and location of death, by examining how insects relate to human remains, and can often times determine if the body being examined was moved after death. •	Forensic Geology is the application of trace evidence found in soils, minerals and petroleum, as applied to a legal setting. •	Forensic Meteorology is an analysis of prior weather conditions, specific to the site being examined. •	Forensic Odontology is the study of teeth- specifically, the uniqueness of dentition. •	Forensic Pathology combines the diciplines of medicine and pathology, as applied to a legal inquiry, to determine the cause of injury or death. •	Forensic Toxicology is the study, evaluation and identification of the effects of poisons, chemicals, or drugs in and on the human body.

These are the broad sub sciences used by forensic department for investigation. A forensic investigator uses knowledge from all these fields to effectively draw a picture of the crime scene. this helps the court of law to give judgemebt and know the motive of the crime committed.

History

The ancient world lacked standardized forensic practices, which aided criminals in escaping punishment. Criminal investigations and trials relied on forced confessions and witness testimony. However ancient sources contain several accounts of techniques that foreshadow the concepts of forensic science developed centuries later, such as the "Eureka" legend told of Archimedes (287–212 BC). The first written account of using medicine and entomology to solve criminal cases is attributed to the book of Xi Yuan Lu (translated as "Washing Away of Wrongs"), written in Song Dynasty China by Song Ci (宋慈, 1186–1249) in 1248. In one of the accounts, the case of a person murdered with a sickle was solved by a death investigator who instructed everyone to bring his sickle to one location. (He realized it was a sickle by testing various blades on an animal carcass and comparing the wound.) Flies, attracted by the smell of blood, eventually gathered on a single sickle. In light of this, the murderer confessed. The book also offered advice on how to distinguish between a drowning (water in the lungs) and strangulation (broken neck cartilage), along with other evidence from examining corpses on determining if a death was caused by murder, suicide or an accident.

Police started using fingerprints for evidence when Juan Vucetich solved a murder case in Argentina by cutting off a piece of door with a bloody fingerprint on it.In 16th-century Europe medical practitioners in army and university settings began to gather information on cause and manner of death. Ambroise Paré, a French army surgeon, systematically studied the effects of violent death on internal organs. Two Italian surgeons, Fortunato Fidelis and Paolo Zacchia, laid the foundation of modern pathology by studying changes that occurred in the structure of the body as the result of disease. In the late 18th century, writings on these topics began to appear. These included A Treatise on Forensic Medicine and Public Health by the French physician Fodéré and The Complete System of Police Medicine by the German medical expert Johann Peter Franck. In 1776 Swedish chemist Carl Wilhelm Scheele devised a way of detecting arsenous oxide, simple arsenic, in corpses, although only in large quantities. This investigation was expanded, in 1806, by German chemist Valentin Ross, who learned to detect the poison in the walls of a victim's stomach, and by English chemist James Marsh, who used chemical processes to confirm arsenic as the cause of death in an 1836 murder trial. Crime Scene Investigation, as related to Forensic Science Directly related to forensic science, though not quite the same, is Crime Scene Investigation (CSI).The primary function of a Crime Scene Investigator is to collect, identify, document, and preserve physical evidence left at the scene of a crime; with the ultimate goal of presenting a court with evidence to identify and apprehend the perpetrator.CSI combines the knowledge and techniques of several different disciplines, including science, mathematics, logic, and law. This highly advanced branch of forensic science utilizes a combination of the scientific method and deductive reasoning to discover and document physical evidence at the scene of a crime; in order to construct a re-enactment of the crime performance- as applied to law enforcement and the legal system.

Digital forensics

Digital forensics (sometimes Digital forensic science) is a branch of forensic science encompassing the recovery and investigation of material found in digital devices, often in relation to computer crime. The term was originally used as a synonym for computer forensics but has expanded to cover other devices capable of storing digital data. Investigations often take one of three forms; forensic analysis (where evidence is recovered to support or oppose a hypothesis before a criminal court), eDiscovery (a form of discovery related to civil litigation) or intrusion investigation (which is a specialist investigation into the nature and extent of an unauthorized network intrusion). As well as identifying direct evidence of a crime, digital forensics can be used to attribute evidence to specific suspects, confirm alibis or statements, determine intent, identify sources (for example, in copyright cases) or authenticate documents. Investigations are much broader in scope than other areas of forensic analysis (where the usual aim is to provide answers to a series of simpler questions) often involving complex time-lines or hypothesis.

Investigative tools

During the 1980s very few specialized digital forensic tools existed and investigators often performed live analysis on media, examining computers from within the operating system using existing sysadmin tools to extract evidence. In the early 1990s a number of tools (such as SafeBack and DIBS) were created to allow investigations to take place without the risk of altering data. As demand for digital evidence grew more advanced commercial tools (EnCase, FTK, etc.) were developed. More recently the same progression of tool development has occurred for mobile devices; initially investigators accessed data directly on the device, these were soon replaced with specialist tools (such as XRY or Radio Tactics Aceso).

Forensic Process

A digital forensic investigation commonly consists of 3 stages; acquisition or imaging of exhibits, analysis and reporting. The first stage, acquisition, involves creating an exact sector level duplicate (or "forensic duplicate") of the media, often using a write blocking device to prevent modification. Both acquired image and original media are hashed (using SHA-1 or MD5) and the values compared to verify the image is accurate. During the analysis phase an investigator usually recovers evidence material using a number of different methodologies (and tools). In 2002 the International Journal of Digital Evidence referred to this stage as "an in-depth systematic search of evidence related to the suspected crime". In 2006, forensics researcher Brian Carrie described a more "intuitive procedure" in which obvious evidence is first identified after which "exhaustive searches are conducted to start filling in the holes" Once evidence is recovered the information is analyzed to reconstruct events or actions and to reach conclusions, work that can often be performed by less specialist staff. When an investigation is complete the investigator presents his data, usually in the form of a written report, in lay person’s terms.

FORENSIC DOCUMENT EXAMINATION

A document may be broadly defined as anything that bears marks, signs, or symbols which have meaning or conveys a message to someone. Document Examination, as an established field of scientific study, came into being early in this century as a means of identifying forgery and establishing the authenticity of documents in dispute. It grew out of the need of The Court to be able to correctly evaluate document evidence. It has been stated that "Forgery was practiced from the earliest times in every country where writing was the medium of communication" (The Law of Disputed and Forged Documents, J. Newton Baker). It was especially profitable in those earlier times of general public illiteracy. For the reason that most of an examiner's work involves some form of handwriting problem, the field is sometimes referred to as "Handwriting Identification" and the practitioner as a "Handwriting Expert". Albert S. Osborn, with the publication of his book Questioned Documents in 1910, is rightfully credited with laying the foundation of this field of forensic examination. Scope of Document Examination •	Identification of handwriting and signatures •	Identification of typewriters •	identification of check writers •	identification of photocopies •	Detection of alterations, additions, deletions, or substitutions

Handwriting Identification Handwriting identification is based on the principle that, while handwriting within a language tends to be alike to the degree that we can meaningfully read it, there are individual features that distinguish one person's writing from that of another. Just as no two people are exactly alike, the handwritings of no two people are exactly alike in their combination of characteristics. There are, of course, natural variations within the handwriting of each individual. These variations must be closely and carefully studied by the examiner, so that he can distinguish between what is a "variation" and what a “difference” is. .

The examiner must also be cognizant of the differences between "class characteristics" and "individual characteristics". Class characteristics are those which are common to a group such as a particular writing system, family grouping, foreign language system, or professional group. Individual characteristics are those which are personal or peculiar letters or letter combinations, which, taken together, would not occur in the writing of another person.

Handwriting identification is a comparison study requiring authenticated specimens of known handwriting from the individual(s) concerned. These are closely compared to the handwriting characteristics exhibited by the questioned writing in order to determine authorship. Like must be compared to like: printing to printing and cursive to cursive, with comparable letters, letter combinations, words, and numerals.

Identification of Typewriters and Checkwriters

With regard to typewriters, questions arise as to whether a series of documents were prepared on the same typewriter; what make/model of typewriter was used; or when was the typed document produced?

Typewriters are identifiable as to make and model by means of class characteristics such as manual/electric, fabric ribbon/carbon film ribbon, typebars/daisywheel/ball element, typeface design, and so on. Machines may acquire individualizing characteristics to varying degrees due to use or misuse, damage, and general wear. The degree of success in a given case will vary with the type of machine with which the examiner is faced.

Check writers, also known as check protectors, may be identified as to manufacturer by its mechanism and typeface design, and individualized by accidental characteristics resulting from damage and wear and tear.

Identification of Indented Writing

Indented writing is an imprint which may be left on the underlying pages when the top sheet of paper is written upon. This impression of the writing is influenced by pen pressure and thickness of the paper. Indented writing is very useful as a form of connecting evidence, such as tying a robbery note to a writing pad recovered from a suspect. Classically, indented writing was identified and deciphered by means of low angle oblique light and photography. More recently, an instrument known as an Electrostatic Detection Apparatus, or ESDA, is now used to produce a visual image of the indented writing on transparency film. This procedure is non-destructive, and rather non-detectable.

Detection and Decipherment of Obliterations and Alterations:

These examinations are performed in order to detect whether a portion of a document has been altered, some portion rendered not readily visible, or some text added. If an obliteration/alteration is identified, then the method is determined and described, and if possible the text of the obliterated entry deciphered. Instruments such as a Video Spectral Comparator (VSC) assist in this study. The VSC allows the examiner to examine the document through infrared illumination using an infrared sensitive CCD camera as a detector. The image is examined by viewing on a monitor, and digital image processing through a computer. This is very useful in ink differentiation.

forensic engineering

Forensic engineering is the investigation of materials, products, structures or components that fail or do not operate or function as intended, causing personal injury or damage to property. The consequences of failure are dealt with by the law of product liability. The field also deals with retracing processes and procedures leading to accidents in operation of vehicles or machinery. The subject is applied most commonly in civil law cases, although may be of use in criminal law cases. Generally the purpose of a Forensic engineering investigation is to locate cause or causes of failure with a view to improve performance or life of a component, or to assist a court in determining the facts of an accident. It can also involve investigation of intellectual property claims, especially patents.

History

As the field of engineering has evolved over time so has the field of forensic engineering. With the prevalence of liability lawsuits in the late 1900's the use of forensic engineering as a means to determine culpability spread in the courts. Dr. Edmond Locard (1877–1966) was a pioneer in forensic science who formulated the basic principle of forensic science: "Every contact leaves a trace". This became known as Locard's exchange principle.

Investigation

Vital to the field of forensic engineering is the process of investigating and collecting data related to the materials, products, structures or components that failed. This involves inspections, collecting evidence, measurements, developing models, obtaining exemplar products, and performing experiments.

Analysis

FMEA and fault tree analysis methods also examine product or process failure in a structured and systematic way, in the general context of safety engineering. However, all such techniques rely on accurate reporting of failure rates, and precise identification, of the failure modes involved. There is some common ground between forensic science and forensic engineering, such as scene of crime and scene of accident analysis, integrity of the evidence and court appearances. Both disciplines make extensive use of optical and scanning electron microscopes, for example. They also share common use of spectroscopy (infra-red, ultra-violet and nuclear magnetic resonance) to examine critical evidence. Radiography using X-rays or neutrons is also very useful in examining thick products for their internal defects before destructive examination is attempted. Often, however, a simple hand lens to reveal the cause of a particular problem. Trace evidence is sometimes an important factor in reconstructing the sequence of events in an accident. For example, tire burn marks on a road surface can enable vehicle speeds to be estimated, when the brakes were applied and so on. Ladder feet often leave a trace of movement of the ladder during a slipway, and may show how the accident occurred. When a product fails for no obvious reason, SEM and Energy-dispersive X-ray spectroscopy (EDX) performed in the microscope can reveal the presence of aggressive chemicals that have left traces on the fracture or adjacent surfaces. Thus an acetal resin water pipe joint suddenly failed and caused substantial damages to a building in which it was situated. Analysis of the joint showed traces of chlorine, indicating a stress corrosion cracking failure mode. The failed fuel pipe junction mentioned above showed traces of sulfur on the fracture surface from the sulfuric acid, which had initiated the crack. Forensic materials engineering involves methods applied to specific materials, such as metals, glasses, ceramics, composites and polymers.

Applications Most manufacturing models will have a forensic component that monitors early failures to improve quality or efficiencies. Insurance companies use forensic engineers to prove liability or no liability. Most engineering disasters (structural failures such as bridge and building collapses) are subject to forensic investigation by engineers experienced in forensic methods of investigation. Rail crashes, aviation accidents, and some automobile accidents are investigated by forensic engineers in particular where component failure is suspected. Furthermore, appliances, consumer products, medical devices, structures, industrial machinery, and even simple hand tools such as hammers or chisels can warrant investigations upon incidents causing injury or property damages. The failure of medical devices is often safety-critical to the user, so reporting failures and analyzing them is particularly important. The environment of the body is complex, and implants must both survive this environment, and not leach potentially toxic impurities. Failures that occur early in the life of a new product are vital information for the manufacturer to improve the product. New product development aims to eliminate defects by testing in the factory before launch, but some may occur during its early life. Testing products to simulate their behavior in the external environment is a difficult skill, and may involve accelerated life testing for example. The worst kind of defect to occur after launch is a safety-critical defect, a defect that can endanger life or limb. Their discovery usually leads to a product recall or even complete withdrawal of the product from the market. Product defects often follow the bathtub curve, with high initial failures, a lower rate during regular life, followed by another rise due to wear-out.

Forensic photography

Forensic photography, sometimes referred to as forensic imaging or crime scene photography, is the art of producing an accurate reproduction of a crime scene or an accident scene using photography for the benefit of a court or to aid in an investigation. It is part of the process of evidence collection. It provides investigators with photos of victims, places and items involved in the crime. Pictures of accidents show broken machinery, or a car crash, and so on. Photography of this kind involves choosing correct lighting, accurate angling of lenses, and a collection of different viewpoints. Scales, like items of length measurement or objects of known size, are often used in the picture so that dimensions of items are recorded on the image.

Methods

Crime or accident scene photographers usually capture images in color but also in black and white. Color pictures are generally preferred because color may be an important aspect of the trace evidence. Pictures from surveillance cameras are a growing source of evidence for courts, as are pictures taken by bystanders on mobile phones. Digital photographs usually have an automatic date and time marker on each image, so that authenticity can be verified. Due to continued advances in digital technology and software, digital single-lens reflex (DSLR) cameras are increasingly being used by law enforcement agencies.

Forensic Photography

While most forms of photography are enjoyed simply for fun, forensic photography is serious business. Also known as crime scene photography and forensic imaging, forensic photography is used to document crime scenes and help police and investigators bring those responsible to justice. These crime scene photographs are often used in the courtroom to give the jury a true picture of what happened, as well as to document and preserve evidence. The job of the forensic photographer is to accurately reproduce the accident or crime scene so that the evidence can be preserved and eventually used in a court of law. Forensic photography can mean everything from photographing a dead body where it fell to taking pictures of a crumpled front bumper from an accident scene. In order to accurately document a crime scene, accident scene or other event, forensic photographers need to focus on things like choosing the proper lighting and using the right lenses and angles to accurately represent what happened. In addition, it is important for forensic photographers to shoot from a variety of different viewpoints in order to provide more complete information. Forensic photographers also often use scales in their photographs. These scales provide important information about the relative size and position of various objects in the photo, and that information can be particularly useful in courtroom situations. Even though forensic photography has been around nearly as long as the photograph itself, the field continues to grow and change. Forensic photographers and the police forces they support are using all sorts of images in their work, including still images and videos from camera phones, traffic cameras and other sources. Skillful police investigators and forensic personnel must often piece together images from a variety of sources, including traditional crime scene photographs, images taken by passersby and video pulled from static surveillance cameras, in order to provide a true picture of what really happened. Providing the investigators, the witnesses, the victims and ultimately the jury with a true picture of the crime scene.

Forensic psychology

Forensic psychology is the intersection between psychology and the criminal justice system. It involves understanding criminal law in the relevant jurisdictions in order to be able to interact appropriately with judges, attorneys and other legal professionals. An important aspect of forensic psychology is the ability to testify in court, reformulating psychological findings into the legal language of the courtroom, providing information to legal personnel in a way that can be understood. Forensic psychologists provide sentencing recommendations, treatment recommendations, and any other information the judge requests, such as information regarding mitigating factors, assessment of future risk, and evaluation of witness credibility. Forensic psychology also involves training and evaluating police or other law enforcement personnel, providing law enforcement with criminal profiles and in other ways working with police departments. Forensic psychologists work both with the Public Defender, the States Attorney, and private attorneys. Forensic psychologists may also help with jury selection.

Forensic psychology practice

The forensic psychologist views the client or defendant from a different point of view than does a traditional clinical psychologist. Seeing the situation from the client's point of view or "empathizing" is not the forensic psychologist's task. Traditional psychological tests and interview procedure are not sufficient when applied to the forensic situation. In forensic evaluations, it is important to assess the consistency of factual information across multiple sources. Forensic evaluators must be able to provide the source on which any information is based. Unlike more traditional applications of clinical psychology, informed consent is not required when the assessment is ordered by the court. Instead, the defendant simply needs to be notified regarding the purpose of the evaluation and the fact that he or she will have no control over how the information obtained is used. Forensic psychologists perform a wide range of tasks within the criminal justice system. By far the largest is that of preparing for and providing testimony in the court room. This task has become increasingly difficult as attorneys have become sophisticated at undermining psychological testimony. Evaluating the client, preparing for testimony, and the testimony itself require the forensic psychologist to have a firm grasp of the law and the legal situation at issue in the courtroom, using the Crime Classification Manual and other sources. This knowledge must be integrated with the psychological information obtained from testing, psychological and mental status exams, and appropriate assessment of background materials, such as police reports, prior psychiatric or psychological evaluations, medical records and other available pertinent information.

Forensic Psychologist A forensic psychologist is someone who studies the actions and motives of criminals, and applies this research to other criminals. He or she usually has a degree in psychology, criminology, or both. Forensic psychologists work in many different areas of the justice system. Some work in courtrooms, while others work for police departments. A forensic psychologist may also work in prisons or detention centers.

it is hard to narrow down exactly what a forensic psychologist does. Because there are so many different branches of psychology (social, cognitive, behavioral, and so on) and so many types of crimes (arson, murder, robbery, and others), there are many different things that a psychologist may do. It is usually based on the psychologist's education and history. A forensic psychologist who works in prisons as a therapist for inmates has a very different job than the forensic psychologist who does profiling for the FBI. A forensic psychologist may act as an expert witness in court cases. As an expert witness, a psychologist provides the judge and jurors with the psychological facts relevant to the crime He They may also help to advise the judge on what sort of sentence should be handed out, based on the perpetrator’s likelihood to continue the criminal behavior. The psychologist may be consulted again every time the perpetrator is up for parole. Some forensic psychologists study the accuracy of eyewitness testimony, some work with youthful offenders, and some work with victims and their families. With such a wide field of possible study, there is almost no limit to what a forensic psychologist can do.

Forensic toxicology

Forensic toxicology is the use of toxicology and other disciplines such as analytical chemistry, pharmacology and clinical chemistry to aid medical or legal investigation of death, poisoning, and drug use. The primary concern for forensic toxicology is not the legal outcome of the toxicological investigation or the technology utilized, but rather the obtaining and interpreting of the results. A toxicological analysis can be done to various kinds of samples. A forensic toxicologist must consider the context of an investigation, in particular any physical symptoms recorded, and any evidence collected at a crime scene that may narrow the search, such as pill bottles, powders, trace residue, and any available chemicals. Provided with this information and samples with which to work, the forensic toxicologist must determine which toxic substances are present, in what concentrations, and the probable effect of those chemicals on the person. Samples A urine sample is urine that has come from the bladder and can be provided or taken post-mortem.A blood sample of approximately 10 ml (0.35 imp fl oz; 0.34 US fl oz) is usually sufficient to screen and confirm most common toxic substances. A blood sample provides the toxicologist with a profile of the substance that the subject was influenced by at the time of collection; for this reason, it is the sample of choice for measuring blood alcohol content in drunk driving cases.Hair is capable of recording medium to long-term or high dosage substance abuse. Chemicals in the bloodstream may be transferred to the growing hair and stored in the follicle, providing a rough timeline of drug intake events. Oral fluid is the proper term, however saliva is used commonly. it is composed of many things and concentrations of drugs typically parallel to those found in blood. Sometimes referred to as ultra filtrate of blood.Other bodily fluids and organs may provide samples, particularly samples collected during an autopsy. In highly decomposed bodies, traditional samples may no longer be available. The vitreous humour from the eye may be used, as the fibrous layer of the eyeball and the eye socket of the skull protects the sample from trauma and adulteration. Other common organs used for toxicology are the brain, liver, and spleen.

Detection and Classification

Detection of drugs and pharmaceuticals in biological samples is usually done by an initial screening and then a confirmation of the compound(s), which may include a quantization of the compound(s). The screening and confirmation are usually, but not necessarily, done with different analytical methods. Every analytical method used in forensic toxicology should be carefully tested by performing a validation of the method to ensure correct and indisputable results at all times. A testing laboratory involved in forensic toxicology should adhere to a quality program to ensure the best possible results and safety of any individual. The choice of method for testing is highly dependent on what kind of substance one expects to find and the material on which the testing is performed. Biological samples are more complex to analyze because of factors such as the matrix effect and the metabolism and conjugation of the target compounds. Gas-liquid chromatography is of particular use in examining volatile organic compounds.The compounds suspected of containing a metal are traditionally analyzed by the destruction of the organic matrix by chemical or thermal oxidation. This leaves the metal to be identified and quantified in the inorganic residue, and it can be detected using such methods as the Reinsch test, emission spectroscopy or X-ray diffraction.

Forensic archaeology

Forensic archaeology, is the application of archaeological principles, techniques and methodologies in a legal context. Forensic Archaeologists are employed to locate, excavate and record buried remains, the variety of such targets is large and each case is unique in its requirements. However whilst the types of target that forensic archaeologists are asked to investigate are diverse the most common can be generally grouped as follows: •	Buried small items or personal effects from a victim of crime, which may be used to corroborate a statement or contain other evidential value. •	Potential gravesites, forensic archaeology attempts to locate and recover any human remains whilst also recording all evidence in association with the remains to reconstruct events that took place prior to the burial of the victim or victims. •	Surface body disposals where a recent victim has been concealed under fallen walls, tree branches, rubbish etc. •	Mass graves, where the recovery of remains is focused on both evidential recovery for future indictments (e.g. The War Crimes indictments in the International Criminal Court) and the identification of individuals remains for surviving relatives which may form a crucial role in reconciliation and breaking the cycles of violence that can continue to occur over generations in such conflicts. •	Civil cases involving buried evidence (e.g. locating former fence lines and steam courses in boundary disputes)

Applications

Forensic archaeologists participate in both the location and excavation of buried remains, recovering human remains, personal effects, weapons, stolen goods, and other potential evidence of the crime or mishap. Forensic archaeology has developed alongside disciplines including archaeological object conservation, as knowledge of the chemical and biological processes involved in the degradation of materials is required for both forensic archaeology and archaeological conservation. The forensic archaeologist studies and predicts the survival of items buried within the ground to explain the pattern of evidence found, whereas the archaeological conservator studies the same processes to stop them further destroying archaeological artifacts. Study of the degradation processes of a human body after death correlates to the survival of associated items and trace evidence useful to law enforcement or other authorities.

Methods

Forensic archaeologists are field archaeologists employing a high degree of skill, knowledge and experience in field craft and technological methods to help locate, recover and interpret buried objects/evidence. The technological methods employed include geophysical prospecting, aerial photography, satellite imagery, surveying and excavation. When dealing with human remains the traditional disciplines associated with archaeology can also be of benefit to an investigation and the study of osteoarchaeology (the archaeological study of the skeleton). This has led, in the UK, to the adoption of the US field of study of forensic anthropology, which uses the human skeletal remains to help determine the age, sex, height, manner of death etc. of an individual.

Forensic anthropology

Forensic anthropology is the application of the science of physical anthropology and human osteology in a legal setting, most often in criminal cases where the victim's remains are in the advanced stages of decomposition. A forensic anthropologist can also assist in the identification of deceased individuals whose remains are decomposed, burned, mutilated or otherwise unrecognizable. The adjective "forensic" refers to the application of this subfield of science to a court of law. Forensic anthropologists can help identify skeletonized human remains.Forensic anthropological techniques can be used to assist in the recovery of remains, assess age, sex, stature, ancestry, and analyze trauma and disease. They may also testify in court as expert witnesses.

commonly used chemicals in forensic science

There are four kinds of chemical reagents used to expose invisible, or latent, fingerprints. They are cyanoacrylate, silver nitrate, iodine, and ninhydrin

Cyanoacrylate The trade name for cyanoacrylate is super glue. Cyanoacrylate is the active ingredient that makes up 98% of Super Glue. This item has become a very practical and innovative forensic tool. When cyanoacrylate is heated or mixed with sodium hydroxide (NaOH), it releases fumes that interact with the amino acids that are found in the fingerprint residues found on an object, thus making a white print.

Silver Nitrate Silver nitrate is a chemical ingredient found in black-and-white photographic film. When silver nitrate is applied to a latent fingerprint, the chloride found in fingerprint residue interacts with the silver nitrate and forms another compound called silver chloride. This new compound reveals a black or reddish-brown fingerprint in the presence of ultraviolet light.

Iodine the third chemical used to reveal latent fingerprints is iodine. When heated up, crystalline iodine releases iodine fumes into a fuming chamber, where the iodine interacts with the oils found in the latent print thus producing a brownish colored fingerprint. Unfortunately, this kind of print has a tendency to fade rather quickly. Therefore, it must be captured on film right away or fixed by spraying it with a "fixing solution" made of water and starch. This fixing solution allows the print to last for weeks or even months in lieu of a few minutes.

Ninhydrin The fourth kind of chemical reagent used to reveal latent fingerprints is ninhydrin. Ninhydrin, also known as triketohydrindene hydrate, has been used for many years to reveal latent fingerprints. An object suspected of containing latent fingerprints is sprayed with a solution of ninhydrin. It may take several hours for the fingerprints to show up due to the fact that ninhydrin reacts very slowly with the oils found in the fingerprint. However, heating up the object to a temperature of 80 to 100 degrees Fahrenheit can reduce the reaction time. The resulting fingerprint will be a purple/blue print.

Forensic Chemists

Forensic chemistry encompasses organic and inorganic analysis, toxicology, arson investigation, and serology. Each method of analysis uses specialized techniques and instrumentation. The process may be as simple as setting up a density gradient column to compare soil samples or as complicated as using a mass spectrometer or neutron activation analysis to characterize an unknown substance. A wide array of laboratory techniques and instrumentation is used in forensic studies. This includes ultraviolet, infrared, and visible spectrophotometery; neutron activation analysis; gas chromatography and mass spectrophotometery; high pressure liquid chromatography; and atomic absorption spectrophotometery. The techniques and instrumentation chosen depend on the type of sample or substance to be examined. The fact that most samples examined are not pure substances, but are often mixed with dirt or debris, presents a major challenge to the forensic chemist. This may also be an advantage, as every substance collected at a crime scene is a unique mixture of chemical compounds that can ultimately be identified. Arsonists, for example, often use accelerants such as gasoline or kerosene to speed combustion and spread flames in the interior of a building. A forensic chemist may collect samples of burned and unburned materials, extract the volatile hydrocarbons, and separate the components for analysis by gas chromatography.

Testing for Alcohol Accidents caused by intoxicated drivers kill nearly 15,000 persons a year in the United States alone (almost half of fatal auto accidents are alcohol-related), so a Breathalyzer kit is standard equipment in most police squad cars or state patrol vehicles. Breathalyzers are used to estimate the blood alcohol content of drivers suspected of being intoxicated; the driver may appear sober, but still have a blood alcohol level above the legal limit. Although it is impractical to take blood samples on the highway, research has shown that the concentration of ethanol in the breath bears a definite relationship to its concentration in blood. Many communities have now set a legal limit of 0.08 percent (meaning that 100 milliliters [3.38 fluid ounces] of blood would contain 0.08 grams [0.0028 ounces] of ethanol). In fact, authorities now consider that a person's driving ability is probably impaired at a blood ethanol level of 0.05 percent. The person being tested blows through a tube, which bubbles the breath through a solution of chemicals containing sulfuric acid, potassium dichromate, water, and silver nitrate. Oxidation of the alcohol results in the reduction of dichromate ion to chromic ion, with a corresponding change in color from orange to green. An electrical device employing a photocell compares the color of the test solution with a standard solution, giving a quantitative determination of the alcohol content. The test provides a quick and reproducible determination of the amount of alcohol in a person's breath and is a numerical measure of the amount of alcohol in the bloodstream. Use of a chemical test helps to avoid subjective opinions of sobriety and provides reliable evidence for court proceedings. The test can be readily and quickly administered by trained law enforcement personnel, but forensic chemists test and calibrate the equipment and testify to its accuracy.

Fingerprinting Fingerprints on smooth surfaces can often be made visible by the application of light or dark powder, but fingerprints on checks or other documents are often occult. Occult fingerprints are sometimes made visible by the use of ninhydrin, which turns purple due to reaction with amino acids present in perspiration. Fingerprints or other marks are also sometimes made visible by exposure to high-powered laser light. Some fingerprints can be treated with chemical substances, resulting in a pattern that fluoresces when exposed to light from lasers. Cyanoacrylate ester fumes from glue are used with fluorescent dyes to make the fingerprints visible.