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Crime Scene Management

Tamara Golson

CRJ 311 Forensics

September 16, 2019

Introduction

The use of forensic science has led to many criminals’ sentences and exonerations by the courts in the country. The collection and analysis of evidence by detectives and experts from crime scene highly influence the decisions of the courts. Despite the introduction of technology in the field of forensic science, certain types of evidence do not require the advanced technology found in labs. The crime scene environment which includes physical evidence such as blood splatter and shoe marks does not necessarily require laboratory analysis. However, the evidence collected from the same can be used to admit a case in a court of law. The collection and testing of on-the-scene evidence and comparison to the laboratory analysis results are very important in any case as it offers specificity of the suspects. This paper aims at identifying different types of evidence that undergoes preliminary testing and a description of the types of testing done on the scene of the crime. The paper will go further to detail reasons why some evidence is tested on-scene while others should not. The paper will also compare field tests with lab examinations and compare and contrast laboratory and preliminary results. Lastly, similarities and differences on acceptability of results from laboratory and on-scene will be offered.

Types of evidence subjected to preliminary testing

Types of ground tests include trace evidence, weapons, impressions, body fluids, hair fibers and questionable documents. According to Robertson, Vignaux, & Berger, (2016) a crime scene rarely lacks evidence from the suspects. “They always leave or take something from the scene” For instance, the crime scene will have at least a hair fiber, fingerprints or any other physical evidence. It is the evidence that provides a start for a start of the case and identification of suspects.

Two types of testing done on the scene

Physical matching forms the first type of testing done on the ground. This involves any physical damages like door break, signs of struggle, blood platters, the arrangements of the kitchen, signs of celebration which can be shown by the number of plates and glasses on the table among other physical evidence that might be available (Morrison, Watts, Hobbs, & Dawnay, 2018).

The second type is the blood spatter analysis. the examination of blood sprays for a crime scene does not require special equipment. The tests can be done preliminary by the use of amino acids. The evidence can quickly indicate the cause of death of the victim even before laboratory examinations are done (Becker & Dutelle, 2018).

Reasons why some evidence should be subjected to preliminary testing on the scene while others should not

Physical material indicators during investigation are crucial in solving any case (Jones, 2018). This includes minor details such as gunshot residue on the hands of the suspect, traces of explosives which deteriorate quickly. This compared to other evidence such as hair fibres, and fingerprints which require laboratory testing provides crucial evidence in solving a case (Becker & Dutelle, 2018).

Explain how the on-scene test compares to laboratory testing

Blood samples or fingerprints were taken from the scene are tested in the lab. After the results have been obtained, the DNA results are compared with that of the suspect to confirm if the two samples match. Jones, (2018) asserts that the results come in either of the three dimensions. Exclude the suspect, show inconclusive results, or identify/confirm the presence of the suspect on the scene. Although the results may confirm or exclude the suspect, they are not the final determinants of the suspect's guilt as other evidence is examined to be used before the Jury.

Compare and contrast the results yielded by preliminary field versus laboratory testing

Using on-scene examination provides more powerful intelligence as compared to that of a laboratory. This is attributed to the challenges that may hinder the processing of secondary evidence. For instance, in a case where the suspect used gloves to commit the crime thus providing no physical evidence for DNA (Bradshaw, Denison & Francese, 2016).

Both pieces of evidence are used in supporting each other for instance confirming the presence of a suspect.

Compare and contrast admissibility of on-scene versus laboratory testing at trial

Using lab examinations during trial has faced challenges but still overrules the on-scene evidence use. This is attributed by the similarity of causes of crimes, for instance, pulmonary oedema may cause death the same way a drug overdose will. Therefore, through laboratory examination, the particular cause of death for the victim is determined (St John, 2018).

All the two methods of testing require the best handling of evidence to avoid contamination. For instance, bullet fragments must be carried in different bags to avoid scratching the same way touching on physical evidence with gloves will contaminate scene (Murdoch, 2011).

Conclusion

The examination and testing of evidence both on-scene and in the laboratory differs. This is dependent on the types of evidence, and admissibility of the evidence on trial. Through a timely examination of the evidence on the scene with the support of the DNA results, criminal cases are solved with ease.

References

Becker, R. F., & Dutelle, A. W. (2018). Criminal investigation. Jones & Bartlett Learning.

Bradshaw, R., Denison, N., & Francese, S. (2016). Development of operational protocols for the analysis of primary and secondary fingermark lifts by MALDI-MS imaging. Analytical Methods, 8(37), 6795-6804.

Jones, N. S. (Ed.). (2018). 2018 impression, pattern and trace evidence symposium. Research Triangle Park, NC: RTI Press. https://doi.org/10.3768/rtipress.2018.cp.0006.1805

Morrison, J., Watts, G., Hobbs, G., & Dawnay, N. (2018). Field-based detection of biological samples for forensic analysis: Established techniques, novel tools, and future innovations. Forensic science international, 285, 147-160.