The role of a state crime lab is integral as it aims at working with physical evidence and investigating crimes. When crime scene investigators arrive at units, they pay attention to every detail and gather material for analysis. In this work, a training program for candidates for a crime lab will be developed through three lessons. They include the explanation of physical evidence to identify purposes, the discussion of the differences between class and individual characteristics of physical evidence, and the evaluation of the class characteristics’ importance. The scope of the investigation may be considerably narrowed through the prism of physical evidence and its major attributes.
Physical Evidence Categories
The first lesson for crime scene investigators is about the categories of physical evidence. Any criminal scene investigator should know that physical evidence is any object that is found at the crime scene and can be used as evidence. In Baxter’s (2015) discussion, there are four main types of evidence: testimonial (a witness tells a story), demonstrative (a demonstration is offered), circumstantial (reasonable circumstances are mentioned), and real or physical (what it is). According to Williams (2016), the range of physical evidence is large, including various “tool marks, clothing, fibers, footwear impressions, firearms, explosives and their residues, glass fragments, paint flakes, soil, drugs and IT equipment” (p. 180). Compared to eyewitness evidence, whose credibility may be questioned, physical evidence cannot be influenced or lie. It is a foundation of a crime scene that claims about what actually happened.
Evidence may be used for identification (physical or chemical identity) or comparison (determination of a common origin between objects) purposes. Identification is characterized by almost absolute certainty of evidence, and comparison maintains the discussion of properties in accordance with standards and suspect samples. In a criminal investigation, the collection and analysis of physical evidence cannot be ignored because it results in the possibility to prove or disprove some aspect of a crime in court.
Physical evidence may be categorized into class characteristics and individual characteristics. Class characteristics contain properties associated with a group, not an individual or another single source. It is usually used to reduce the number of suspects, taking into consideration the blood type, the presence of fibers or paint, or broken glass (Baxter, 2015). Individual characteristics are properties attributed to a particular source with a high certainty degree (Williams, 2016). Fingerprints, toolmarks, or DNA are examples in this category of physical evidence. Individual characteristics promote the exclusion of other suspects, relying on a piece of evidence found at the crime scene and proved in the court.
This lesson sheds light upon the basics of physical evidence and its relation to other forms of evidence found at the crime scene. Identification and comparison are the purposes that have to be fulfilled in any investigation, and the task of an investigator is to understand that the use of different evidence leads to different outcomes. Class and individual physical evidence categories have their unique peculiarities, and candidates should not be confused by this variety.
Class Characteristics vs. Individual Characteristics
It is an obligation of any crime scene investigator to differentiate physical evidence according to its characteristics, either class or individual. Therefore, the theme of the second lesson is to explain the existing differences. Compared to individual characteristics where a particular source or a person is chosen for identification, class characteristics are focused on a group of objects of people. Sample turns out to be the major distinctive feature of these two types of physical evidence.
Class characteristics do not allow matches that can be applied to a single suspect, and individual characteristics make this match possible. The value of class characteristics is questioned because most evidence is characterized in terms of this group, which confuses an investigator and does not give enough reasons for suspecting (Baxter, 2015). For example, fiber of the suspect’s clothes and fiber of the victim’s clothes may be similar. Forensic evaluation results in similarities, and only circumstantial evidence can be applied to the court (Baxter, 2015). In the same case, the class characteristic aims to determine or refute a toolmark and suspect’s belonging to it (Horsman & Errickson, 2019). Class characteristics help begin an investigation and establish certain norms and standards for further development of the events.
Individual characteristics have a number of significant benefits and supporters. Their usefulness lies in the possibility of identifying a tool and its established standards (Horsman & Errickson, 2019). Marks on objects that are caused by irregularities on the surface used for manufacturing may be effectively applied to identify a source. Such examples include knives or bullets, and criminalists have a database with the already identified marks that can be used to simplify an investigation procedure.
At the end of the second lesson, a candidate is able to distinguish the differences between class and individual physical evidence and understand what kind of information should be gathered. It is wrong to think that the identification of differences may result in prioritizing one type and diminishing another. This work aims to assist crime scene investigators with gathering and evaluating evidence with respect to its type.
Importance of Class Evidence
Crime scene investigators should understand the importance of class characteristics. It will be a theme for the third and final lesson to prepare candidates for work with evidence. During the beginning stages of an investigation process, a team faces a number of objective scientific data. Class physical evidence promotes the corroboration of events and the creation of a clearer picture for further investigation. In addition, there is a chance to encounter several items that originate from different sources. If enough class evidence is gathered and analyzed, there is a possibility to turn circumstantial evidence into real and demonstrative evidence with an object or a person to be at a certain place at a certain time. In this case, the value of class characteristics increases, promoting new possibilities and aspects of the same case.
A final part of the training program focuses on the identification of the value of class characteristics in physical evidence. Despite the fact that this type includes the evaluation of a group of people or subjects, investigators should not underestimate class evidence in their work. Its worth is in the possibility to begin analysis of the crime scene and concentrate on and working with potential suspects.
Conclusion
In general, the role of a state crime lab is integral in any criminal investigation. The goal of this training program is not only to prepare employees and make them aware of the basics of physical evidence. This course is a unique opportunity to understand why different types of evidence matter. Candidates must realize that a possibility to gather evidence for a group of people or for an individual is highly appreciated and can never be ignored.
References
Baxter, E. (2015). Complete crime scene investigation handbook. Boca Raton, FL: CRC Press.
Horsman, G., & Errickson, D. (2019). When finding nothing may be evidence of something: Anti-forensic and digital tool marks. Science & Justice. Web.
Williams, C. (2016). Physical evidence. In R. Sutton, K. Trueman, & C. Moran (Eds.), Crime scene management: Scene specific methods (2nd ed.) (pp. 180-208). West Sussex, England: John Wiley & Sons.