I am currently conducting research in policing and forensics for a 90minute screenplay for my final media project at uni.
Trying to keep research as broad as possible, so using books, papers, documenteries, internet links etc. but would also be grateful for any other information, so if you work in the above fields or doing a degree in forensic science, or have better knowledge on these subjects than I do, I would really appreciate your help.

Basically need to know about police arrest procedure, questioning and how long you can legitmately hold a suspect on the basis of very strong DNA evidence and what happens if the evidence doesnt match the suspect. A basic time scale.

On the forensic side how long certain procedures take, for example taking and matching DNA samples, process of autopsy.

In both fields what would happen if there was so much concrete evidence, such as fibres, hair, DNA etc but absolutely no one to pin it to because of no eye witnesses, would you call around the local area for example and ask people to voluntarily give samples?

Please PM me if you think you can help

Thanks
xxxx

well as a scientist, iI'd say,

Something can only be conclusively proven in the negative.

I.E. you can say "definitely not" , but you can only say "possibly yes".

a sample of hair found at the crime scene can either definitely not be comparable to the hair from suspect "A" , or it can be a probable match.

A genetic (dna) match between an alleged father and the baby he is alleged to have fathered, can only say that the tests prove that the putative father definitely was not, the father of the child, or could say that there is a strong probability of a match.

PT

the probabilities of the positive match are generally so high that the evidence is accepted as fact though in court.

there have certainly been instances of the police collecting samples from many people within an area of a crime, but they're pretty rare...