To protect the evidence and record interactions with that evidence, criminal investigators establish a chain of evidence, sometimes called a chain of custody. This involves documentation of evidence location and each person who has handled it. In court, a defense attorney may question the origin or processing of evidence, and the investigator can point to the chain of evidence to refute any claims of contamination or improper collection or storage methods.

• Identify the key roles in the chain of evidence.
• Explain how each role contributes to the chain of evidence.
• Where does the greatest responsibility lie for the proper handling of evidence?
• Did assumptions made about evidence by law enforcement when building a case help or complicate a case? Explain your reasoning
• Choose a response that is different from your own.
• Explain how your colleague's position has changed your perception or understanding.

Key Roles in the Chain of Evidence

The chain of custody simply details the record of persons who had control over evidence, from the time it was initially obtained to its' introduction at court (Brandl, 2018). Every person who handles evidence plays a key role. From the moment of discovery and collection, every person must take care to follow the correct procedures to ensure evidence can be admissible in court later. Brandl discussed the person who: collected the evidence, transported it to the department or lab, logged it or received it and who received it for "final inventory" are key roles (p. 115).

How Each Role Contributes to the Chain of Evidence

The person that initially collected the evidence starts the chain of custody. They should ensure that the boundaries of the crime scene have been secured. A sketch or diagram may be necessary before handling evidence. Photographs should be taken, both from close and long range (Brandl, 2018). The evidence must be collected and packaged properly. Any related documentation needs to be thorough and accurate.

The transportation role ensures that the evidence is preserved while in transit from one place to another. Evidence, if not properly secured, could be damaged in transit. Further, a cross-contamination scenario could take place if two or more pieces of evidence come into contact. If the evidence went to a lab, lab workers must ensure that proper testing and evidence handling procedures are also followed.

The person that logs or receives the evidence must ensure that the evidence is properly documented and sealed. It must be stored in a secure environment with appropriate temperatures. It should be kept in a place free from potential tampering.

The person receiving it from the lab or the department must ensure that the chain of custody is adjudicated to its final location. This would need to be documented thoroughly.

Greatest Responsibility for Proper Handling of Evidence

As mentioned above, everyone who handles evidence plays a key role. Whoever handles the evidence has the greatest particular responsibility in that moment to properly handle and document the evidence.

Assumptions and Building a Case

Law enforcement assumptions regarding evidence hinder a case. One must follow the facts and not allow personal bias or opinion to guide he or she. Assumptions may lead an investigator to attempt to prove their theory. This could lead to someone ruling out evidence which would otherwise be beneficial. It is in everyone's best interests, not least of which any potential suspect(s), to not allow assumptions in a criminal investigation.

Brandl, S. (2018). Criminal investigation (4th ed.). Thousand Oaks, CA: SAGE Publications.