Forensic evidence analysis

Audio engineering is the capture, enhancement, and reproduction of sounds. It requires an aesthetic appreciation of music and sound quality, a scientific understanding of sound physics, and a technical fe-miliarity with recording equipment and computer software. This applied science is essential to the music industry, film, television, and video game production, live television and radio broadcasting, and advertising. In addition, it contributes to educational services for the visually impaired and to forensic evidence analysis. 

Forensic science laboratories are generally divided into separate specialty areas. These typically include forensic toxicology, soHd-dose dmg testing, forensic serology, trace evidence analysis, firearms and tool mark examination, questioned documents examination, and latent fingerprint examination. Laboratories principally employ chemists, biochemists, and biologists at various degree levels. In some specialty areas, eg, firearms examination, questioned... 

TXRF has recently also been used to discriminate between green PE garbage bags, based on Ti, Pb, Cr and Cu analysis (forensic evidence) [288], XRF provided a more effective method of discrimination when compared to IR spectrometry or DSC. 

The use of activation analysis in criminal investigations (forensic activation analysis) is also well established. The basic idea here is to match the trace-element distributions found in bullets, paint, oil, and so on found at the scene of a crime with the trace-element distributions in objects found with criminal suspects. Such identification is rapid and nondestructive (allowing the actual evidence to be presented in court). Moreover, the probability of its correctness can be ascertained quantitatively. Other prominent examples of the use of forensic activation analysis involve confirmation of the notion that Napoleon was poisoned (by finding significant amounts of arsenic in hair from his head) and the finding that the activation analysis of the wipe samples taken from a suspect s hand can reveal not only if he or she has fired a gun recently but also the type of gun and ammunition used. 

In addition to the analysis of arson crime scene evidence, thermal desorption has been used for the analysis of residual volatile agents in street drugs and the analysis of stains on forensic evidence. Samples are heated to volatilize water and organic compounds. The organic analytes may then be separated by gas chromatography (Figure 22.2). 

Lombardi, G. (1999). The contribution of forensic geology and other trace evidence analysis to the investigation of the killing of Italian Prime Minister Aldo Moro. J. Forensic Sci. 44, 634-642. 

The sequence of events associated with FDR examination is usually as follows the initial incident, apprehension of suspects, transporting of suspects to police station, sampling of suspects at police station (swabs of hands, face, head hair, and seizure of clothing), submission of items to the laboratory, sampling of clothing at the laboratory, sample preparation, analysis of samples, interpretation of results, preparation of statement of witness report, and the presentation of forensic evidence in court. 

Keratin is a natural single-strand polymer consisting of chains of amino acids, with a high proportion of the two sulfur-containing amino acids cysteine and methionine. Keratin is the polymer of hair and nails. The sulfur atoms account for keratin s ability to bond to arsenic, mercury, and lead. Hair analysis has played an important role in forensic evidence in cases of poisoning, and it has been possible to diagnose the extent to which famous people in history were affected by these toxic elements provided a sample of their hair has been preserved. 

ICP-MS has also been used to measure trace elements in archaeological native silver artifacts [345] in order to identify their geographical origins. The low detection limits provided by ICP-MS allowed analysis of trace elements on 3 to 15 mg of sample. The passivation of alloy steels using acid solutions has been studied by XPS measurements of the solid in combination of ICP-MS analysis of the passivation solutions [346,347]. When bullets are crushed on impact, striations cannot be used for identification. The percentage of antimony, trace element composition, and lead isotope ratios in bullets was measured for forensic evidence [348]. The lead isotope ratios were found to be the most useful evidence. 

APPLICATIONS OF ANALYTICAL PYROLYSIS TO THE ANALYSIS OF FORENSIC EVIDENCE, CULTURAL MATERIALS, ETC. 

Advantages Most forms of chemical analysis require vaporization, dissolution, or alteration of the analyzed sample in some way. Neutron activation analysis is a nondestructive process that can be used to study liquid, solid, or gaseous samples. Sensitive items, such as forensic evidence, meteorites, or artifacts, can be analyzed without harm. 

The chemical characterization of forensic evidence from a crime scene or the criminal has some different requirements from that of many other types of chemical analysis. High sensitivity is important because the quantity of material for examination is often limited to minute traces found at the scene. The material under scrutiny must be characterized as comprehensively as possible to ensure maximum discrimination from other material in the same class. Forensic laboratories are multiinstrument facilities required to deal with many types of evidence found at a crime scene therefore, the routine methods used should preferably employ relatively inexpensive instrumentation. In order to protect integrity, samples should be analyzed as received if possible and any workup minimized. The method should preferably not be labor intensive. Pyrolysis-gas chromatography (Py-GC) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) have proven to be an effective means of satisfying these requirements in many forensic science laboratories. - ... 

Re-examines methods in areas with a long history of analysis by pyrolysis including microorganisms, coatings and adhesives, textiles, synthetic polymers, cosmetics, and forensic evidence... 

DNA analysis is now a basic tool in the establishment of links between biological evidence and comparison samples. It has reached such a widespread use and its power is so impressive that it is probably the best-known forensic analytical method in the general public. Because of the need of high-tech instruments and sophisticated analysis kits, standardization has been surprisingly quick to come, favored by the almost monopoly of a couple of providers in this field. As a consequence, forensic DNA analysis is being practiced worldwide using almost identical tools and protocols. 

Ramotowski, R.S. Regen, E.M. The effect of electron beam irradiation on forensic evidence. 2. Analysis of writing inks on porous surfaces. J. Forens. Sci. 2007, 52, 604-609. 

Forensic Genetics. Forensic genetics is the use of human genetics in criminal or paternity cases. For example, DNA testing on blood, saliva, or other tissue can be used to determine the source of evidence, such as blood stains or semen, left at a crime scene. Forensic DNA analysis is also used to determine paternity and other kinship. Finally, with the increasing use of forensic genetics since the 1990 s, some incarcerated prisoners have been released after it was clearly determined that they could not possibly have been guilty of crimes they were convicted of, as DNA evidence eliminated them from suspicion. 

Successful forensic trace evidence analysis is characterized by the ability to locate, collect, manipulate, identify, and compare microscopic particles. However, sample poverty is common in legal investigations. The sample size is frequently limited, and oftentimes only a portion of the sample can be used, pending the need for additional analysis. This places a further burden on the analyst, techniques, or instruments used. Accordingly, microscopy is the first choice for most forensic examinations. 

In the case of the assassination of President John F. Kennedy, a key piece of forensic evidence was provided by the analysis of bullets and fragments recovered. Research thb case, describe how the elemental analysis was dcme, and discuss some of the limitaticms of the instrumental technique used. How would such an analysis be accomplished today ... 

One of the major problems in the analysis of forensic evidence is posed by samples containing biological material from more than one source. The large number of discrete alleles at multiple loci make STR multiplexes and excellent tool for identifying components of mixtures. 

Local and state forensic laboratories generally do not engage ia excipient testing. Most provide quaUtative and quantitative analysis of the evidence to determine if an Ulegal substance is present and if so, the amount of the dmg present. The quantity of dmg seized by the authorities may be important ia jurisdictions which give enhanced sentences for larger amounts of the pure dmg, or ia some cases the total weight on the dmg and diluent ia possession of the defendant. 

Trace Evidence. Trace evidence (23) refers to minute, sometimes microscopic material found during the examination of a crime scene or a victim s or suspect s clothing (see Trace AND residue analysis). Trace evidence often helps poHce investigators (24) develop connections between suspect and victim and the crime scene. The theory behind trace evidence was first articulated by a French forensic scientist the Locard Exchange Principle notes that it is not possible to enter a location, such as a room, without changing the environment. An individual brings trace materials into the area and takes trace materials away. The challenge to the forensic scientist is to locate, collect, preserve, and characterize the trace evidence. 

Microscopists in every technical field use the microscope to characterize, compare, and identify a wide variety of substances, eg, protozoa, bacteria, vimses, and plant and animal tissue, as well as minerals, building materials, ceramics, metals, abrasives, pigments, foods, dmgs, explosives, fibers, hairs, and even single atoms. In addition, microscopists help to solve production and process problems, control quaUty, and handle trouble-shooting problems and customer complaints. Microscopists also do basic research in instmmentation, new techniques, specimen preparation, and appHcations of microscopy. The areas of appHcation include forensic trace evidence, contamination analysis, art conservation and authentication, and asbestos control, among others. 

Forensic analysis is usually required for the collection of data in the course of determining whether legislation has been infringed. The customer requires that, above all, there is an unbroken chain of evidence from the time the samples were taken to the presentation of evidence in courts of law. In the laboratory this will include documentation and authorization for sample receipt, sample transfer, sub-sampling, laboratory notebooks, analytical procedures, calculations and observations, witness statements and sample disposal. All of these aspects can be called as evidence in court. 

A comprehensive approach to a states response to a chemical terrorism includes having a plan not only for the crisis and consequence management phases of the incident, but also for all elements required for complete resolution of the event. This may include the necessity to definitively establish whether chemical agents were used, to provide supporting evidence to confirm other analyses, or to provide the forensic proof required to support a criminal prosecution. The collection and analysis of biomedical samples - blood, urine or other tissue from affected humans or animals - is one of the means for providing such information. Although current capabilities such as urinary thiodyglycol excretion or plasma cholinesterase activity can be performed, there is scope for far more sensitive and specific assessments that overcome the limitations of these approaches. 

Trace analysis of explosives is of major importance in forensic and environmental applications [6]. In forensics, the applications include analysis of postexplosion residues and identification of traces of explosives on suspects hands, clothing and other related items. The results of these analyses are not only necessary for the investigation of a bombing but can also serve as evidence in court. 

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