Suppose I have a video surveillance system. Down the road from me a serious crime occurred. Investigating officers canvass the neighborhood looking for leads. I, being a "good" American citizen, choose to not talk to "police" nor answer their questions. The police, noticing my video surveillance system, ask to inspect any recordings that might have caught something of interest to their investigation. Again, "flexing" my rights, I ask them to leave and not contact me again about the matter without a warrant.
Some variation of this occurs frequently in fiction, and, if those fictional stories are to be believed, it is generally impossible for crime investigators to secure either a warrant or a subpoena for either persons or devices that they believe only by circumstance might have information that could assist their investigation. Is this correct?
Now, lying to an investigator, or altering, destroying, or concealing evidence, can subject one to various "obstruction of justice" charges. So, of course, I do nothing to alter, destroy, or conceal my video surveillance.
But now, feeling a little high on my constitutional rights, I call the head of the investigating agency and say something to the effect of, "Some of your agents were down here today and seemed interested in my video surveillance footage. I haven't examined it, and I am not altering it, so I don't know what's on it or whether it could help them. But I paid good money for that system, and not for public benefit. I'd be willing to give them access in exchange for $5,000." Could this offer of potential evidence in exchange for money run afoul of any law?
(A less cavalier demand might be, "I'd really like to help, but I need $5,000 to pay my lawyer to ensure that my rights are preserved.")
Again, if fiction is to be believed, crime investigators only get access to this third-party evidence through persuasion. They never volunteer to pay for access, and they are never asked. So is this only because crime fiction writers lack imagination, or is there a legal reason?