I acknowledge this is a point of view deeply believed by many. And I acknowledge that there have indeed been cases where corrupt officials broke the rules or acted in ways that undermine the integrity of the law enforcement departments or agencies in which they serve.
Examples that come immediately to mind when I think of this include the four white police officers that murdered George Floyd, and then Attorney General Bill Bar front-running the Mueller investigation, to benefit Donald Trump; hindering the report's release and putting a narrative-defining spin on it, instead of simply letting the report speak for itself.
I am one of those Americans who "desperately want to put our full faith in federal law enforcement," but because I know officers are human and human corruption sometimes happens, I also know we cannot give law enforcement a blank check. Law enforcement knows that too, which is why they have inspector generals and internal affairs departments, and why we sometimes see police officers investigate and arrest fellow officers.
One of the times I reported for jury duty and sat in the pool being questioned by the judge and attorneys, I heard a prospective juror tell the judge she could never side against the police. Judging from her emotional tone, she seemed to be talking from her heart. She meant what she said. Her son is a police officer, she said, and a police officer's word is always true, always unimpeachable. Now she may have said that to get disqualified from jury duty (which happened) but my sense was she deeply believed that. In her mind, if the police arrest someone, they are guilty and the police always act appropriately. And if they don't, there is certainly an alternative theory that can be produced to take their side and make the police always right.
Just as it is not wise to believe the police, or the Justice Department, is always right and their motives are always pure. it is not wose to believe they are always wrong and their motives are always corrupt.