Forensic evidence

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. 

Scent as Forensic Evidence and Its Relationship to the Law Enforcement Canine, Charles Mesloh, http //www.uspcak9.com/training/forensicScent.pdf... 

Informed debate and decisions on such important matters as the depletion of the ozone layer, acid rain and the quality of waterways all depend on the data provided by analytical chemists. Forensic evidence also often depends on chemical measurements. National and international trade are critically dependent on analytical results. Chemical composition is often the basis for the definition of the nature of goods and tariff classification. In all of these areas not only is it important to get the right answer but it is essential that the user of the results is confident and assured that the data are truly representative of the sample and that the results are defendable, traceable and mutually acceptable by all laboratories. 

M.M. Zanoni, A. Morris, M. Messer and R. Martinez, Forensic evidence canines Status, training and utilization . In Proceedings of the 1998 American Academy of Forensic Sciences, San Francisco, CA, 1998. 

The trial of the Birmingham Six took place in June 1975. Except for the confessions and some (very little) circumstantial evidence, the prosecution based its case on forensic results. It was obvious that forensic evidence was extremely important confessions could have been obtained by force, but what convincing explanation could one have for the presence of NG on his hands a few hours after an explosion ... 

But where did he come from Tie may have been raised in the same region where his body was found, or he might have been a newcomer to the area, or just traveling through. To determine which is the case, chemists and biologists have developed techniques that make use of certain isotopes. As with forensic evidence, these isotopes can be found in Otzi s teeth and bones. 

Analytical chemistry impacts on every aspect of modern life. The food and drink we consume is tested for chemical residues and appropriate nutritional content by analytical chemists. Our health is monitored by chemical tests (e.g. cholesterol, glucose), and international trade is underpinned by measurements of what is being traded (e.g. minerals, petroleum). Courts rely more and more on forensic evidence provided by chemistry (e.g. DNA, gun-shot residues), and the war on terrorism has caused new research into detection of explosives and their components. Every chemical measurement must deliver a result that is sufficiently accurate to allow the user to make appropriate decisions it must be fit for purpose. 

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). 

Hence, forensic research is exactly what revisionists, starting with Robert Faurisson, have called the search for material evidence. The revisionists demand for such material evidence is entirely consistent with the normal practice of modem law enforcement. Also, as is generally acknowledged, forensic evidence is more conclusive than eyewitness testimony or documentary evidence. 

Turner, B. D. and Wiltshire, P. E. J. (1999). Experimental validation of forensic evidence A study of the decomposition of buried pigs in a heavy clay soil. Forensic Sci. Int. 101,113-122. 

Forensic evidence in a court case, or a drugs test on an athlete, is often front page news. A collection of essays on various aspects of the history of forensic science has appeared.340 An overview of forensic chemistry in nineteenth century Britain... 

The SEM has proved to be an invaluable instrument in its application to forensic evidence materials. Several widely different successful applications of the SEM-EDA instrumentation to actual criminal cases have been presented. 

Non-Polymeric Materials. Waxes, soaps, greases, asphalts, oils. Complex mixtures of hydrocarbons of different molecular weight when treated to a common thermal history (such as slow program-cooling from above the melt) give complex but highly repeatable characteristic DSC melting profiles (16,17). In the absence of any other forensic evidence, these thermal profiles should be sufficiently specific and repeat-able to be definitive evidence. 

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. 

There are two very important factors involved in the processing of suspects for forensic evidence ... 

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. 

Q (S3 Imagine that you are a lawyer. You are representing a client charged with possession of a controlled substance. The prosecutor introduces, as forensic evidence, the empirical formula of the substance that was found in your client s possession. How would you deal with this evidence as a lawyer for the defence ... 

In Chapter 22, Herr et al. describe a monoclonal antibody used to test for human albumin in body fluids. The development of this monoclonal antibody was aimed at forensic evidence, but if (and it must be tested) degradation processes do not destroy the antigenic site that this antibody recognizes, it could be used for archaeological samples. Certainly as these techniques are developed they will prove valuable in the studies of objects that are suspected of containing blood. For example, these newer methods could help further define an artifact like the Shroud of Turin, which is described in Chapter 23. 

The development of monoclonal antibody probes specific to human albumin is the subject of this chapter. These antibody probes and the test methods were developed and evaluated for use in forensic science situations. Although these methods work well on soluble extracts of dried blood stains that are several years old, they have not been applied to archaeological material. The successful development of monoclonal antibodies specific to the human albumin molecule suggests that an approach similar to that used for identifying human tissues and blood on forensic evidence could be applied to any species of interest to the archaeologist. 

Activity Research the types of chemical tests that investigators use to gather forensic evidence after a crime. Prepare a media article explaining the forensics investigation to the public. 

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

Copper(II) hydrogen arsenite (CUHASO3) is a green pigment once used in wallpaper in fact, forensic evidence suggests that Napoleon may have been poisoned by arsenic from his wallpaper. In damp conditions, mold metabolizes this compound to trimethylarsenic [(CH3)3As], a highly toxic gas. 

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