As anyone who's watched any of the CSI shows knows, they try to show investigations of various crimes being solved by the application of various forensic techniques. In some cases these are done reasonably accurately except (often) for speed of processing. In others, they're screamingly funny in their wrongness (most obvious is the common "let's enhance this video to see what's in this tiny little part of the background" resulting in this amazingly clear video of someone stabbing someone in the back).
One of the most common plot threads is trying to identify or obtain for identification some DNA for comparison. I know they do this stuff at lightspeed compared to real life, but one thing I *have* wondered about is this: generally they show that they have a "database" of DNA samples to search, and I'm wondering:
1) Are there actually decent-sized databases of people's DNA already on file that could be searched that way?
2) If so, who's IN these databases, who can access them, and when/how do people get put into them in the first place?
3) Does this vary across the country? I.e., if I'm in, say, Los Angeles do I have access to databases X and Y, but not A and B, but in New York I have A, B, and X but not Y?