Force the police to prove that they deleted the results of the analysis, I assume. And yes, if they'd get to that point, the police would need to produce a watertight audit trail. Depending on how much will there is to actively fight back, possibly in retailiation to discourage further breaches of procudure, they might be able to archive a lot due to the disconnection from national security and the legal standing they have on this. Also, German courts usually order looser pays all. As Attorney fees are capped according to some tables, in relation to the sum being fought over, this usually isn't a problem. You don't get interest back though.