Identification, Collection and Preservation of Trace Evidences - Research Paper Example

? Identification, Collection and Preservation of Trace Evidences Identification, Collection and Preservation of Trace Evidences Introduction Trace analysis in crime scenes entails evaluating evidences, which in most instances do not easily fit into a particular group or individual (Dutelle, 2011). Therefore, trace analysis involves looking up into not just the size of physical evidence but the quantity of the evidence, since in some cases relatively bigger quantities may be present but only trace quantity are available. Furthermore, it also considers the fact that suitability of evidence for analysis will depend on sample size and discrete characteristics, given that it may not always be possible to determine an affirmative physical match. Hence, this paper discusses trace elements found in firearms, Paint, fibers, glass, and fingerprints. Discussion Fibers Most fiber piece contains similar physical nature with majority of such pieces found in crime scene are either made from polyester or nylon. The class characteristics includes weave pattern, dyes present, cordages, fabric impressions and tears (Brown, 2001). Thus, fiber in a crime scene is hard to identify without using microscopic and a combination of chemical and instrumental tests. Fibers are normally found in fabric abrasions with some trapped within torn material. In scenes involving hit-and-run motor vehicles fibers occur on scratched sections, and in burglary incidences they are normally found in tattered screens, clothing and broken glass (Brown, 2001). Collection is based on length of the fibers, such that if the fibers are undersized or few in numbers, the investigator is required to wrap the region or the entire product comprising the fibers in a paper (DuPre, 2013). However, if the fibers are large or in greater numbers, the investigator should place them in a bindle that is then placed in a sealed and marked coin envelope (Dutelle, 2011). The fibers should be picked up on tape if the lab in that jurisdiction permits it but with defined requirements. All clothing of belonging to an individual from which the fibers are found to have come from should also be picked for comparison purposes. Every garment should be placed on uncontaminated sheet of paper before separately rolling it up after marking the exhibit. Loose fibers should not be positioned directly into mailing wrapper since they can be lost (Buckles, 2010). Firearms Class characteristics found in firearms largely arises from the impact of bullets fired from the firearm, such as number and width of grooves, course of twist, or bullet diameter, in addition to the caliber and rifling patterns inside the barrel (DuPre, 2013). The cartridges and casings also have class characteristics like breech marks, impressions created by firing pin, in addition to extractor and ejector marks (Buckles, 2010). Firearms are easy to identify when there is transfer of the individual distinctiveness, chiefly striated marks left from the firearm to bullet and cartridge ammunition component (Brown, 2001). In terms of collection, the firearm should not be picked up through placing any other object in the barrel terminal. Unfired cartridges should not be left inside the magazine if the magazine is separated from the gun even as the rifles and shotguns must not be dismantled (Buckles, 2010). The investigator should not clean the firearm bore, chamber, or cylinder until they are submitted or even try to fire the firearm before it is evaluated in the Lab. Moreover, firearm having a cartridge inside the chamber must never be transported by any method since the firearm is not cocked or on-safety (Brown, 2001). The investigator should also record serial number, model, the firearm make, in addition to the weapon caliber (Hess & Orthmann, 2009). Marking should be done using an inconspicuous method that does not detract from its value, since copy serial numbers are sometimes on different firearms of a similar make and general-type. Nonetheless, model numbers and the firearm patent numbers should not be confused with serial numbers (Dutelle, 2011). The firearm should be placed in tough cardboard or even wooden boxes that are packed in order to avert shifting during transit. If blood, fingerprints or any other item that can be relevant to the investigation exists on the firearm, the investigator should place an uncontaminated paper around the firearm, before sealing it using tape, or just simply fasten it down using strings, in order to avoid movement and contact with other items or loss of sample during transportation (Buckles, 2010). Fingerprint Class characteristics identified in fingerprints includes those characteristics that identify the print based on ridge pattern. The ridge patterns belong to groups and they include arches, the loops, and the whorls, with most people having loops (DuPre, 2013). Nonetheless, fingerprints are easy to identify since they have individual characteristic with no two people having similar print pattern. Most prints can be identified by dusting a scene with black powder before being lifted using a segment of a clear-tape. However, fluorescent is used in dark regions or multicolored areas with Ninhydrin being used in prints located in paper or else cardboard surfaces (Buckles, 2010). Fingerprints are identified on document, glass, metal, or other smooth surfaced item (Brown, 2001). A photograph of the fingerprint latent should also be obtained. Latent fingerprint should be marked in distinctive manner, and in an approach that does not damage or obliterate likely latent fingerprints (Brown, 2001). The major precaution is avoiding adding fingerprints to at hand evidence or damaging existing ones. Those objects with latent fingerprints should be picked up by avoiding widespread touch using gloves or uncontaminated handkerchiefs. Those massive items with latent fingerprints like metal or firearms should be positioned on wooden and strong cardboard before fastening them down using strings in order to avoid shifting or contact with other items during transportation (Dutelle, 2011). However, bottles or glasses containing fingerprints need to be positioned vertically on top of a board and positioned at the bottom of the box while the base is surrounded using nails in order to hold it in position (DuPre, 2013). Papers or documents having latent fingerprints needs to be positioned independently inside cellophane or else manila envelope and sandwiched between double sheets of solid cardboard. Paint Paint class characteristics point towards the category the paint came from objects like automobile, house, or from nail polish (Brown, 2001). Hence, it is hard to identify paint without comprehensive chemical analysis of that particular paints several layers. However, manufacturers my use similar suppliers in coming up with layers and colors and this makes it hard to identify paint without conducting a detailed pyrolysis gas-chromatography analysis (Dutelle, 2011). Paint evidence is largely found in instances like hit-and run automobiles, and equipments used by criminals in breaking into a building. This also comprises items that are used gain entry into the house, the safe insulations, and plastic items normally contain paint traces. If the entire paint chips were transferred to a garment such that the flakes have numerous layers, the paint chips are mostly located on the ground next to impact position. In cases whereby paint was transferred to garment, the investigator should examine the clothing with emphasis placed on sections revealing pressure varnish or tears (Buckles, 2010). The paint should not be removed, but instead the investigator should mark the clothing before carefully wrapping the garment by rolling it inside a paper. In case of motor vehicles, they normally have several colors such that paint transferred will only characterize the color of that particular section of the vehicle that encountered the victim (Hess & Orthmann, 2009). In terms of collection, the paint can be flaked off through winding the metal slightly, or otherwise the investigator should scrape off the paint with a clean knife-blade and every layer of paint should be collected down to the metal, before placing every sample in separate containers (Buckles, 2010). Notably, the investigator should cut out just about the mark. The investigator should not make marks, since it will result in transfers of paint such that traces discovered later will be considered insignificance evidence due to tampering (Brown, 2001). Loose paint chips should be placed in paper bindle, but samples should not be placed directly in envelopes, but in paper bindles initially. In case of automobiles, if cross transfers have taken place, the investigator should gather the contaminated samples from every automobile within adjacent sections, in order for the specimens to be distinguished between transferred paint and the paint initially present on the car (Brown, 2001). In terms of burglary incidences, every sample from the scene areas and which reveal fresh damage should be collected, since paints are normally unlike in type and composition in diverse regions even when the color is similar (Buckles, 2010). Hence, the investigator should wrap the terminals containing the objects in clean paper or seal them using tape in order to prevent loss. Diminutive paper bindles are used to collect and store several paint samples. This entails taping one section of the bindle to the plane of the building or car just under the region where the sample has been collected (Brown, 2001). Scotch tape, which is not stapled, is used to seal the bindle, and the paint sample should not be placed directly into envelopes, since the unsealed cracks inside the envelope corners will lead to loss and even contamination. Glass Class characteristics in glass evidences include refractive index, the density, color, and chemical makeup (Hess & Orthmann, 2009). Hence, since the individual characteristic of glass evidences is only when the fragments are able to fit together it is hard to identify a particular source. Glass evidences include broken windows during burglaries, vehicles headlights in hit-and-run incidences and broken bottles. In terms of identification, the investigator should look at direct impact regions, and other items such as shoes or suspects clothing (Buckles, 2010). However, the search should not be restricted to regions of direct impact, especially in motor vehicles hit and run incidences whereby headlight glasses are scattered some distance further as the vehicle leaves the scene. In such cases, every glass still intact inside the shell must be recovered, and this includes filaments, intact lamp sockets sections, glass-envelope, in addition to the sealed headlight unit (Buckles, 2010). In case a new glass is suspected to be reinstalled, it should be removed in order to examine minor chips remaining inside the shell and from earlier broken lens. In terms of collection, glasses acquired from different areas especially burglary and hit and run should be stored in distinct containers since more than one form of glass can be present (Hess & Orthmann, 2009). However, smaller fragments should be stored inside paper bindles before being coined in envelopes, case boxes, or inside film-can that are marked and totally sealed (Brown, 2001). Individual glass pieces should be separated using cotton or even tissue inside sealed and marked boxes, in order to prevent breakage or destruction of edges during transportation (Dutelle, 2011). In case of smaller broken windows, the entire window should be taken to lab, but in larger windows, several samples can be taken from separate areas of that window. This will help in the comparison of edges, fracture lines, identification of hackle marks, comparison of surface abrasions and even in identifying contamination (Brown, 2001). In case of bottles, every broken pieces and the untouched glass should be recovered. Conclusion This paper observes that when collecting trace evidences, the investigator should be certain that every item is rightly identified, especially by assessing the class characteristics of that physical evidence. This is because suitability of evidence for analysis depends on sample size and discrete characteristics. Secondly, every piece should be marked and sealed appropriately in order to avoid damaging or contaminating the evidence during delivery. Although identification, collection and preservation are seemingly autonomous of each other, an error made in one of them will produce significant outcome on another. Hence, investigators should consider accuracy, specificity, dependability, and evidence practicality when doing the three activities. References Brown, M. F. (2001). Criminal Investigation: Law and Practice. New york: Butterworth-Heinemann. Buckles, T. (2010). Crime Scene Investigation, Criminalistics, and The Law. Boston, MA: Cengage Learning. DuPre, D. P. (2013). Homicide Investigation Field Guide. NewYork: Academic Press. Dutelle, A. (2011). An Introduction to Crime Scene Investigation. Boston: Jones & Bartlett Learning. Hess, K. M., & Orthmann, C. M. (2009). Criminal Investigation. Boston, M A: Cengage Learning. Read More