Common biological evidence includes which options?

• A. Blood
• B. Semen
• C. Saliva
• D. All of the above

Answer: (D)

Biological evidence in forensic science commonly comes from body fluids that carry DNA. Blood is routinely found at crime scenes and can yield a usable DNA profile, even after drying with proper collection. Semen is frequently encountered in sexual-assault cases and provides DNA, often with high sperm DNA concentration, making it a strong source for identification. Saliva is also common, left on cups, cigarette butts, or bite marks, and contains cellular material that can be analyzed for DNA. These fluids are all biological materials that investigators can collect and test to associate a person with a scene or event. Because each of these fluids can be recovered from a crime scene and yield genetic material for analysis, all of the above represents common biological evidence.