It seems that all famous cases of crimes committed by the FBI originate from abuse of power, meaning they protect one criminal organization to fight another criminal organization, or shoot "bad guys" when it isn't necessary at all. But all these crimes are of the category "we wanted to do good by using bad methods". So, a question: were there any cases in the USA when the FBI committed "traditional" crimes, meaning crimes finalized to personal enrichment and pure increase of power, like Eppolito and Caracappa in the police? I mean, not just abuse of power to do something what originally was supposed to be a positive goal, but entering into the criminal world as a part of it?

I am interested because for example in Russia there are often arrests of gangs composed of entirely of cops, cops committing extortion, robbery etc. There is a recent trial of 2 FSB (secret service) colonels who had a businessman killed to steal and sell a building belonging to him, and then eliminated the hitman as well.
In Italy it's rarer, but here there was a gang of policemen robbers called the "Gang of the white number one" (La banda dell'uno bianca" ("L'uno bianca" - "the white number one" was their car).

Any similar cases in America?