Forensic analysis fingerprinting

Forensic analysis of DNA samples DNA fingerprinting by means of PCR has revolutionized the analysis of evidence from crime scenes. DNA isolated from a single human hair, a tiny spot of blood, or a sample of semen is sufficient to determine whether the sample comes from a specific individual. The DNA markers analyzed for such fingerprinting are most commonly short tandem repeat polymorphisms (STRs). These are very similar to the VNTRs described previously (see p. 455), but are smaller in size. [Note Verification of paternity uses the same techniques.]... 

Some analytes, such as riboflavin (vitamin B2)16 and polycyclic aromatic compounds (an important class of carcinogens), are naturally fluorescent and can be analyzed directly. Most compounds are not luminescent. However, coupling to a fluorescent moiety provides a route to sensitive analyses. Fluorescein is a strongly fluorescent compound that can be coupled to many molecules for analytical purposes. Fluorescent labeling of fingerprints is a powerful tool in forensic analysis.17 Sensor molecules whose luminescence responds selectively to a variety of simple cations and anions are available.18 Ca2+ can be measured from the fluorescence of a complex it forms with a derivative of fluorescein called calcein. 

One extension of blotting techniques that is likely to be expanded considerably in the near future is DNA fingerprinting for forensic analysis, paternity testing, etc. Already, the dioxetane substrate for alkaline phosphatase has been shown to be a useful tool in this endeavor (G4). 

The restriction fragment patterns produced from these loci can be used to identify individuals as accurately as the traditional fingerprint. In fact, this restriction fragment technique has been called DNA fingerprinting and is gaining widespread use in forensic analysis. Family relationships can be determined by this method, and it can be used to help acquit or convict suspects in criminal cases. 

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... 

The last few years have shown increasing applications of TOF-SIMS in forensic science. Preliminary studies in the visualization and analysis of fingerprints indicate that the TOF-SIMS method opens new perspectives for the examination of fingermarks, especially in the imaging of fingermarks in various ions. 

The newer applications involve the field of biotechnology. Proteins produced by genetically altered organisms such as bacteria must be examined to verify that they are identical to the same proteins produced by humans. Also, analysis of DNA from crime scenes is relatively recent. Indeed, DNA analysis and fingerprinting are powerful tools in modern forensics. 

The use of a direct combined (or polyphasic) approach can create highly specific soil fingerprints from normal constituents. This, in addition to the application of appropriate statistical analysis, would make soil analysis a more effective tool for routine forensic work, thus considerably extending its applicability. Indeed, combinations of different data each with its own discriminatory potential may result in probabilities of association or disassociation that even surpass those of techniques such as human DNA. Initial work using a canonical variate analysis has shown discrimination between soil types can be improved by including more analytical data. Figure 11.11 illustrates... 

The comparison of evidence is a well-established function of the forensic laboratory. Fields of expertise such as document examination, fingerprint analysis, firearms examination, as well as a myriad of other types of examination, all rely on the comparison of an exhibit with either a reference collection or another specific exhibit. 

The fact that excited atoms give off specific colors and not a rainbow of colors suggested to Niels Bohr, a Danish physicist, that electrons are permitted in only certain locations within the atom. These locations are called energy levels. Each element behaves in its own unique way when excited by heat or electricity and produces a very specific pattern of lines of color called the atomic spectrum of that element (Figure 8.5). This unique chemical fingerprint is the foundation of atomic spectroscopy, a method of analysis used by forensic and medical laboratories to identify elements... 

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