https://www.techdirt.com/articles/20191119/11492143413/surprising-no-one-fbis-watchdog-says-agency-is-handling-informants-improperly.shtml

Confidential informants are only as trustworthy as their law enforcement handlers. The FBI isn't the only agency to have problems with handling confidential human sources (CHSs), but it's one of the more notorious, thanks to its botched handling of James "Whitey" Bulger.

This questionable legacy lives on, as the FBI's Inspector General reports. "Whitey" Bulger is name-checked early on in the report [PDF], setting an appropriately cautionary tone for the rest of the document.