What type of evidence is often collected from a crime scene for DNA analysis?

Bodily fluids are a critical type of evidence collected from crime scenes for DNA analysis because they contain genetic material that can be used to identify individuals. This includes substances like blood, saliva, semen, or other fluids that may be left at the scene. The ability to extract DNA from these bodily fluids makes them highly valuable in forensic investigations, as DNA profiling can provide definitive evidence linking a suspect to a crime or can help in identifying victims.

Other types of evidence, while useful for various investigative purposes, do not directly yield DNA in the same way that bodily fluids do. For instance, writing samples may help in establishing authorship or intent but do not provide biological material for DNA analysis. Footage from surveillance cameras can offer insights into events leading up to or during a crime, and personal property might help to identify a suspect or connect them to a crime scene, but neither provides the biological evidence necessary for DNA analysis. Thus, in the context of DNA evaluation, bodily fluids are the most relevant evidence collected at a crime scene.