ASIS International (ASIS) Professional Certified Investigator Practice Exam

What common biological material is used in forensic DNA analysis?

1. Red blood cells

2. Saliva

3. Muscle tissue

4. Hair shaft

The correct answer is: Saliva

Saliva is a common biological material used in forensic DNA analysis because it contains a high concentration of DNA, particularly from epithelial cells that are shed from the inside of the mouth. This makes saliva a valuable source of genetic material in forensic investigations, especially in cases such as sexual assault or when a suspect’s identity needs to be confirmed. Saliva samples can be easily collected from various surfaces, making them practical and non-intrusive to obtain. While other biological materials, such as red blood cells, muscle tissue, and hair shafts, can also provide DNA, saliva is particularly advantageous due to its ease of collection and the abundance of DNA present. Blood, for instance, can require more invasive collection methods, and muscle tissue may not be as readily accessible in living subjects. Hair shafts, although they can contain DNA, often provide less reliable results unless the hair is pulled from the root, as the shaft itself carries a limited amount of nuclear DNA. Thus, saliva stands out as a particularly useful and commonly utilized source in forensic DNA analysis.