Northern Virginia Criminal Justice Academy (NVCJA) Practice Exam

In forensic science, what is the purpose of collecting DNA under fingernails?

1. To analyze the suspect's identity

2. To establish a timeline of events

3. To identify defensive actions taken by a victim

4. To link various crime scenes

The correct answer is: To identify defensive actions taken by a victim

Collecting DNA under fingernails serves a crucial role in forensic science, particularly in the context of violent crimes. This action is often associated with defensive wounds, where a victim may have fought back against an assailant. Therefore, the presence of DNA from an attacker under the victim's fingernails can provide compelling evidence that the victim was engaged in a struggle at a specific time and place. This form of evidence can help recreate the events leading up to a confrontation, indicating that the victim may have attempted to defend themselves. Additionally, it can identify the attacker through their DNA, which is vital for establishing leads and creating a suspect profile in criminal investigations. The focus on defensive actions highlights the interaction between the victim and the assailant, making it significant for establishing the dynamics of the incident. In contrast, analyzing a suspect's identity, establishing a timeline of events, or linking various crime scenes do not directly stem from the collection of fingernail DNA, even though they may involve DNA analysis in a broader context. These aspects may rely on other types of evidence or contextual information that are not as specifically tied to the defensive action indicated by the DNA found under fingernails.