Prove the original crime, don’t rely and peripheral procedure like “they lied to a federal agent” (uhh) cop-out. Do your job.
Likewise I’m not don’t of people getting off on “technicalities” (Some more than others)
Sure, no evidence, no crime, but in this case there was evidence that the feds knew about. If you destroy the evidence before the cops know it exists, fair game. But this wasn't it.
As usual, the coverup is worse than the crime. Especially for the guy getting railroaded.