Individual and Class Characteristics of Physical Evidence

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Table of Contents

Abstract
Introduction
Fourth Amendment and Crime Scene Searches
Importance of Collecting and Examining Multiple Sources of Evidence
Challenge of Using Evidence with Class Characteristics
Challenge of Using Evidence with Individual Characteristics
Conclusion
References

Abstract

This paper attempts to discuss the challenges related to the collection and use of evidence with class and individual characteristics. Under the Fourth Amendment to the American Constitution, officers on crime scene searches must be able to not only show the probable cause of the decision to conduct the search or seizure but also have a search warrant provided under oath or affirmation for the collected evidence to be admissible in a court of law. Additionally, it is important to collect and examine multiple sources of evidence with the view to not only increase the odds that a certain match will be realized when two or more specimens of evidence are compared but also ensure that the forensic scientist is able to prove beyond any reasonable doubt that the similarities of the specimens outweigh the dissimilarities.

From the discussion, it is evident that the most significant challenge linked to the collection and use of evidence with class characteristics in court emanates from the inability of forensic scientists to assign exact or even approximate probability values when conducting a comparison of most class-related physical evidence. Similarly, the most significant challenge connected to the collection and use of evidence with individual characteristics concerns the inability of the forensic scientist to state with mathematical exactness the probability that the analyzed specimens are of common origin.

Introduction

The collection of physical evidence through a comprehensive assessment of the crime scene and analysis of forensic evidence is of immense importance by virtue of being the initial step towards the preservation of the forensic value of the evidence for use in attempting to apprehend the perpetrators and ensuring that they face justice in a competent court of law (Lee & Pagliaro, 2013). Research is also consistent that the collection and documentation of physical evidence help the investigators to not only recreate the events leading up to the commission of a crime but also to have an adequate understanding of the events occurring during the commission of a crime and those occurring after the crime has been committed (Fisher & Fisher, 2012).

According to Saferstein (2012), physical evidence is normally assessed by forensic scientists for identification (determining the physical or chemical identity of a substance with the most certainty or assurance that accessible diagnostic techniques will allow) and comparison (the process of determining whether two or more specimens have a common origin). As such, there is a need for investigators to demonstrate a comprehensive understanding of how to collect and examine physical evidence in crime settings, including having the capacity to collect and use evidence with class and individual characteristics in a court of law. In this light, the present paper attempts to illuminate the challenges connected to the collection and use of evidence with class and individual characteristics.

Fourth Amendment and Crime Scene Searches

The Fourth Amendment to the American Constitution is clear that the rights of people and their property should not be violated through unreasonable or unjustifiable searches and seizures (De la Cal, 2016) and that any warrants or guarantees for searches and seizures must be issued upon showing probable cause and supported by oath or affirmation provided by a competent agency, such as a court of law (Hubbart, 2015). According to this amendment, any evidence collected by law enforcement agencies through unreasonable searches and seizures can be declined in a court of law. Similarly, any evidence collected by police officers without an oath or affirmation describing the place to be searched and the individuals/things to be seized may be inadmissible in a competent court of law. This means that officers on crime scene searches must be able to not only show probable cause of the decision to conduct the search or seizure but also have a search warrant provided under oath or affirmation for the collected evidence to be admissible in a court of law.

Importance of Collecting and Examining Multiple Sources of Evidence

It is important to collect and examine more than one questioned, unknown, known, or exemplar item of evidence to not only increase the odds that a certain match will be realized when two or more specimens of evidence are compared but also to ensure that the forensic scientist is able to prove beyond any reasonable doubt that the similarities of the specimens outweigh the dissimilarities (Buckles, 2012; Saferstein, 2012). This attestation is of immense importance in a competent court of law for the evidence to be directly linked to the perceived perpetrator of a crime.

Challenge of Using Evidence with Class Characteristics

Evidence is said to demonstrate class characteristics when it can be linked only to a group and not to a single source, implying that the class characteristics alone cannot allow matches with a single suspect (Fisher & Fisher, 2012). The most significant challenge linked to the collection and use of evidence with class characteristics in court emanates from the inability of forensic scientists to assign exact or even approximate probability values when conducting a comparison of most class-related physical evidence (Saferstein, 2012). For example, a forensic scientist investigating a murder case may be unable to determine the probability that a nylon fiber found on the crime scene originated from a particular sweater, given the fact that we are living in a society that is increasingly reliant on mass-produced goods.

In substantiating such evidence in a competent court of law, the forensic scientist may realize that very few statistical data or approaches are available from which to assign exact or even approximate probability values of the nylon fiber belonging to a particular sweater and not to others. Consequently, credibility issues involving the use of evidence with class characteristics may arise in court as the forensic scientist may not have the capacity to prove beyond any reasonable doubt that the similarities of a crime specimen outweigh any dissimilarity (Buckles, 2012). For example, although class characteristics such as footprints can be used to narrow down a list of possible suspects, it may be difficult for a forensic scientist to argue in court that the footprints belonged to a particular individual without combining this evidence with other typologies of evidence.

Challenge of Using Evidence with Individual Characteristics

In forensic science, evidence with individual characteristics denotes properties or components of evidence that can be ascribed to a unique common source with an exceptionally high level of certainty or conviction (Saferstein, 2012). For example, the matching ridge characteristics of two fingerprints, consistent handwriting characteristics, as well as matching footwear impressions can all be described as physical evidence with individual characteristics since the properties of evidence collected from the crime scene can be attributed to a particular perpetrator with an extremely high degree of certainty. The most significant challenge linked to the collection and use of evidence with individual characteristics in court concerns the inability of the forensic scientist to state with mathematical exactness the probability that the analyzed specimens are of common origin.

This inability is embedded in the fact that it is often difficult for the forensic scientist to develop a particular analytical strategy that could be used to eliminate all but one evidential specimen from consideration. According to Saferstein (2012), most forensic scientists using evidence with individual characteristics work from the assumption that the probability that the specimens are of common origin is so high as to defy mathematical computations or human comprehension; however, the examiner may face difficulties in substantiating such a conjecture beyond any reasonable doubt in a court of law. As such, it may prove difficult to substantiate the conclusion of the common origin of evidence-based probability calculations or the forensic examiner’s own experience. This challenge is further compounded by the fact that the forensic scientist may find it difficult to exclude other specimens based on the typologies of tests that may be readily available to identify a particular specimen, resulting in difficulties in excluding all other specimens from consideration (Buckles, 2012). Lastly, the illuminated challenge is also compounded by the inability of the forensic scientist to exercise control over the quality and quantity of the specimens received for analysis (Saferstein, 2012).

Conclusion

The present paper has attempted to discuss the challenges related to the collection and use of evidence with class and individual characteristics. Drawing from the discussion, it can be concluded that forensic scientists need to have adequate knowledge and understanding of these challenges to ensure that the evidence they produce before a competent court of law is proved beyond any reasonable doubt.

References

Buckles, T. (2012). Crime scene investigation, criminalistics, and the law (2nd ed.). New York, NY: Thomson Delmar Learning.

De la Cal, M.S. (2016). City of Los Angeles v. Patel: The fourth amendment’s “special needs” in the information age. Berkeley Technology Law Journal, 31(1), 1137-1168. Web.

Fisher, B.A.J., & Fisher, D.R. (2012). Techniques of crime investigation (8th ed.). Boca Raton, FL: CRC Press.

Hubbart, P.A. (2015). Making sense of search and seizure law: A fourth amendment handbook (2nd ed.). Durham, NC: Carolina Academic Press.

Lee, H.C., & Pagliaro, E.M. (2013). Forensic evidence and crime scene investigation.Journal of Forensic Investigation, 1(2), 5-12. Web.

Saferstein, R. (2012). Forensic science: From the crime scene to the crime lab (2nd ed.). New York City, NY: Pearson.

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