Which type of evidence is typically collected with a "swab"?

The correct answer focuses on biological evidence, such as saliva or blood, which is conventionally collected using a swab. Swabbing is a method utilized primarily to gather biological samples from surfaces or directly from biological materials. This technique is effective because it allows for the collection of viable cellular material that can be analyzed for DNA, bodily fluids, and other biological indicators relevant to forensic investigations.

When a swab is used, it often involves a sterile applicator with a soft tip designed to absorb moisture and adhere to biological samples. The collected samples can then be analyzed using various scientific methods to establish connections to individuals or to understand the circumstances surrounding a crime.

Other types of evidence listed have different collection methods that do not involve swabbing. For example, physical fingerprints require lifting techniques or powders to be collected from surfaces, digital traces are extracted via electronic forensic techniques, and footprints are usually cast or photographed directly at the crime scene. Each of these methods is tailored to the specific type of evidence to ensure successful collection and preservation for analysis.