In crime scene context, what is a bystander?

• A. Evidence may be contaminated
• B. Evidence may be conclusive
• C. Evidence becomes stronger
• D. Evidence becomes inadmissible automatically

Answer: (A)

Bystanders at a crime scene can contaminate evidence because they are not part of the investigation and may touch or move items, leave behind their own materials, or otherwise alter the scene. This can transfer hairs, fibers, skin cells, or DNA, or disrupt the original arrangement of items, all of which compromise the evidence’s integrity. That's why preserving the scene and restricting access are essential practices in forensics, to minimize contamination and preserve reliability for analysis.

The other outcomes don’t fit because a bystander doesn’t automatically make evidence conclusive, stronger, or inadmissible. Contamination is a risk that investigators manage through proper collection, documentation, and maintaining the chain of custody; admissibility may be challenged if contamination is proven, but it isn’t automatic.