Online Custom «Trace Evidence» Essay Sample
Table of Contents
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- Historical Perspective of Trace Evidence in Forensics
- The Hypothetical Ideal Trace Evidence
- Instruments and Methodology Used in Trace Evidence Analysis
- Toxicological Examination Using Chromatography
- XRF/XRD: Elemental Chemical Analysis
- Inductively Coupled Plasma (ICP) Mass Spectrometry
- Raman Spectroscopy Techniques
- Microscopy and Microanalysis
- Polymerase Chain Reaction DNA Profiling
- Case Studies Showing the Use of Trace Evidence in Criminal Conviction
- The Recent Crisis Rocking Trace Evidence and Criminalistics
- Related Law essays
During criminal litigation processes, the prosecution is usually allocated a responsibility to put their suspects at the crime scene by providing graphical evidence that ties the accused to their offenses and the locale of the crime. At times, the indictment has to rely on the ‘silent witnesses' to solve the criminal cases. The agglomeration of all the material, namely hair, fiber, blood, soil, gunshot residue, DNA, fabric etc. that may have belonged to the subjects of a crime during commission of the offense, has been used to associate suspects with a delinquency and the crime scene as well as to form the large part of trace evidence. To obtain trace evidence, the investigating officer(s) (IO) who conduct(s) a crime scene investigation (CSI) has to preserve a locale of the crime and try to collect as much material as possible in order to ensure a basis for analysis (criminalistics) that can identify suspects in relation to the crime scene., Therefore, trace evidence are well-founded in the history of forensics, but different techniques are essential to analyze the material, which connects the criminal suspect and the crime victim; though recently the entire forensics discipline has faced the scholarly crisis with regard to anomalies and dire limitations.
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Historical Perspective of Trace Evidence in Forensics
The use of trace evidence is as old as CSI, as IOs have always tried to establish links between suspects, victims and crime scenes. However, introducing microscopy in the 20th century forensics presented the commencement of seminal work on trace evidence by such researchers as Reis, Gross and Locard (Roux et al., 2007). The great part of the operations undertaken by forensic analysts and IOs complies with the Locard's ideas that have been so far referred to as the Locard's principle. Locard postulated that every contact must leave a trace, regardless of the magnitude (Blackledge, 2007). However, Burney and Pemberton (2013) posit that the current employment of trace evidence owes to the works of Han Gross and the birth of CSI in the late 19th century. Therefore, a preserved crime scene with all the material unmoved and non-tampered for an ample time as well as properly recorded is requisite in obtaining reliable evidence.
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The Hypothetical Ideal Trace Evidence
Despite the crucial role played by trace evidence in the associative conviction of crime, the admissibility of trace evidence differs greatly. Fingerprints and DNA are highly admissible as evidence compared to other material presented as trace evidence since contact traces do not possess equal evidential value (Roux, Talbot-Wright, Robertson, Crispino, & Ribaux, 2015). Blackledge (2007) argues that the hypothetical ideal trace evidence ought to be nearly invisible so that the suspects are oblivious to its existence and not able to remove it. Moreover, it should have a strong likelihood to be transferred and retained, be highly individualistic, easy to collect, separate and particularly concentrated, easy to characterize, searchable due to the use of computerized databases, as well as resistant to environmental degradation and changes. The more the trace evidence is closely associated with the suspect, the victim and the scene, the higher its evidential value and admissibility will be.
Instruments and Methodology Used in Trace Evidence Analysis
To qualify trace evidence, great collaboration is to be ensured between IOs who conduct CSIs and analysts who analyze residues collected by IOs. The rule of the thumb for CSI, as Hans Gross asserted, is to refrain from any changes of the position, as well as avoid picking or touching anything at the crime scene before everything is described in details in the crime scene report (Burney & Pemberton, 2013). Physical and biological scientists jointly analyze the materials that IOs have gathered in the FBI laboratories (Blackledge, 2007). Thus, the techniques employed for efficient evidence analysis are as follows:
Toxicological Examination Using Chromatography
The technique involves administration of a single chemical substance referred to as an agent to an organism in known amounts. The requirements of the substance under study is for it to be pure. Otherwise, the nature of any present contaminants needs to be carefully considered in order to validate the interpretation of the results (Sharma, Rajveer, Sharma, Mishra, & Tiwari, 2017). In the toxicological examination, poisons are separated from tissues by means of steam distillation as well as differential solvent extraction (Sharma et al., 2017). However, purity verification is always overlooked.
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XRF/XRD: Elemental Chemical Analysis
X-ray Fluorescence (XRF) and X-ray Diffraction are the techniques that have been used in criminalistics for some time. Forensic samples are treated differently in XRF/XRD in a non-destructive manner and provide for confirmatory analysis to verify the integrity of the findings (Sharma et al., 2017). XRF does not affect the evidence; it is applicable to a wide range of samples as well as residues, and it examines physical traces that can associate suspects with victims and the crime scene.
Inductively Coupled Plasma (ICP) Mass Spectrometry
The given technique discriminates glass sheets by exposing the sheets to elevated temperatures and then determining trace impurities. It also uses ablation of laser jets as well as solution sampling to receive iron in glass data by comparing dynamic reaction cell-ICPMS data with the high-resolution ICPMS data (Sharma et al., 2017). Additionally, glass can be examined by LIBS, LA-ICPMS, and µXRF by analyzing and contrasting different irradiation wavelengths.
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Raman Spectroscopy Techniques
The employment of Raman Spectroscopy (RS) is resurging in the forensic science. Raman spectroscopy depends on varying vibration modes for molecules when irradiated under intense monochromatic sources to measure the resultant inelastic scattering of light (Sharma et al., 2017). Furthermore, this nondestructive technique is not time-consuming and provides for microscopic in-situ analyses. Nevertheless, this criminalistics technique of examination of fibers and other materials such as fabrics borrows from the detection of dyes under monochromatic sources.
Microscopy and Microanalysis
Apparently, this is the oldest and the most common technique of criminalistics in analyzing micro evidence. Microanalysis employs microscopes to observe and analyze the material along with other evidence, which is microscopic, that would not be possible without such devices (Sharma et al., 2017). The electron microscope is the most widely used instrument that matches observable features on the samples obtained from suspects, victims or crime scenes. Mostly, Ultraviolet (UV) and Infrared (IR) light as well as electron beams are employed to illuminate the samples. However, only optical, molecular and elemental information can be gained, and microanalysis may require the application of other techniques to acquire sensitive data. Hence, a key method is SEM-EDX (X-ray Spectrometry).
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Polymerase Chain Reaction DNA Profiling
DNA profiling and matching are perhaps the most commonly implemented techniques today, as DNA is an invaluable trace evidence. Matching DNA collected from a victim or a crime scene to the suspect's DNA puts the latter in the locale of the crime. Large repeat units such as the D1S80 were the initial steps in DNA profiling with large amplicon sizes, which would later evolve to short tandem repeats (STRs); moreover, in the late 1990s and the beginning of the 21st century Polymerase Chain Reaction (PCR) will be used (Van Oorschot, Ballantyne, & Mitchell, 2010). PCR allows for genetic information from a minute and low-quality DNA to be generated through the multiplexing of primers. Currently, manufacturers have developed a range of commercial kits that can be utilized for PCR in DNA profiling.
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Case Studies Showing the Use of Trace Evidence in Criminal Conviction
Despite the skills required, the level of technology and the amount of money spent, trace evidence has been used in successful criminal conviction. Asserting that glitter can be a substantial trace evidence in crime conviction, Blackledge (2007) documents three crimes. The first one is the murder in Missouri where glitter on the victim’s jeans, the victim’s bedspread and the suspect’s trousers were profiled to incriminate the accused. The second instance is the Illinois kidnapping and sexual assault in which a derelict was found guilty after glitter was detected on several of his items matching the glitter from the cut-off decoration on the victim’s T-shirt. Finally, the third case is the Florida vehicle homicide in which a mother and a daughter were killed by an intoxicated driver who was sentenced only because of the matching glitter on the pick-up truck’s airbag that hit the victims’ car. Thus, trace evidence is invaluable in criminal conviction, especially if the investigation lacks a credible eyewitness to the crime.
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The Recent Crisis Rocking Trace Evidence and Criminalistics
Despite the significant role that trace evidence have played in the criminal justice system, forensics has experienced crisis as well as some anomalies and serious limitations. A number of reports from various sources, in particular the US National Academies of Science (NAS) report of 2009, have shown that criminalistics is downgraded, has a lot of cost-benefit doubts and its future and admissibility remain uncertain (Roux et al., 2015). Therefore, these critical issues have presented researchers with the question of whether it is possible that trace evidence and forensics in general are slowly declining.
Summarily, the entirety of such material as hair, fiber, blood, soil, gunshot residue, DNA and fabric that may be left by the subjects of a crime in the process of committing the offense have been used to associate suspects with the offense and the crime scene as well as to form the large part of trace evidence. The latter is crucial in providing connections between alleged criminals, victims, and/or locale of a crime, especially if there are silent witnesses' only. DNA and fingerprints are valuable compared to other types of evidence, namely glass fragments. Besides, different techniques have been employed in criminalistics to examine samples. Investigations of criminal cases and conviction of an offense are based on trace evidence. Though forensic/criminalistics have been crisis-struck, trace evidence is quite useful in the criminal justice system; thus, the criminals matters should be tackled with the consideration of trace evidence buttressed in criminalistics.