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Also Be as Unhelpful as Possible for when they're guilty of something unrelated.
Edited by Bisected8 TV Tropes's No. 1 bread themed lesbian. she/her, fae/faer
^^ OP says the crimes are unrelated which defies the idea of suggested trope,
It also doesn't necessarily have to be a worse crime, like the example I used. Embezzling money is certainly bad, but it's not nearly as bad as the potential theft of a nuclear warhead.
In another JAG example, there was a hunt for someone who was murdering prostitutes in ports a navel ship was visiting. When the cast investigated the subjects, they all turned out to be guilty of something serious (one was a rapist, one had beaten up a cross dresser, etc), but none of them had anything to do with the murders. Minor Crime Reveals Major Plot is something of the opposite of what I'm looking for.
Edited by BattleMaster
Check out Big Secret.
That fits better.
The heroes are searching for the perpetrator of a crime. During the investigation, they discover someone who's committed another crime but has no relation to the original crime.
For example, in one episode of JAG there's a search for a missing and presumed stolen nuclear torpedo. During the search, the characters discover and catch someone who's been stealing money from the Navy.
Edited by BattleMaster