Like for example: a drug raid, or they’re accusing you of illegal hacking, or some sort of TheSilkRoad type of stuff.
Assuming the original investigation find no evidence and leads to no charges, could they use the pirated content that you have as a last ditch effort to get you in prison? Not distributing, just personal use.
Not limited to any specific jurisdiction, just want to know what happens in general.
Possession of content – with the unique exception of CSAM – in the USA does not draw a distinction between how it was acquired, whether or not it may have violated a license or copyright. The primary provisions of the Copyright Act of 1976 are to protect the production and distribution of copyrighted works. So unless your stash of content is being hosted on a server for others to access – which constitutes distribution, though one could possibly argue that if no one ever accessed it, it’s not distribution – then the mere possession does not incur criminal liability. Of course, civil liability may attach, meaning that the copyright holder could sue you for the cost of buying a legit license. Though there’s zero reason for the police to pass that info to whomever the copyright holder is. Whether police can gratuitously share investigation info with a third-party is a matter of state law.
But the other potential criminal charge could come from the infamous DMCA, whose provisions make it a crime to circumvent DRMs. Though this provision has an out, whereby certain circumvention is permitted as exceptions for designated purposes, created and renewed through a regulatory process. Outside these exceptions, the standard defense of fair-use for copyright infringement does not apply to a charge of DMCA circumvention. So if the police could put together evidence that your content stash is the product of circumvention, and other evidence shows that you used or have the tools/software to perform that circumvention, that’s technically a charge which could be leveled.
This would take a colossal amount of effort, for something which generally has to be brought by the (federal) US Attorney’s office, rather than a state-level District Attorney. So realistically, this would only really be considered if you somehow managed to annoy an FBI investigator enough. And even then, it’s quite petty to charge DMCA circumvention alone.
If your content was purely acquired through download-only means – as in, not BitTorrent – then I can’t think of what criminal charge could be raised. But IANAL.