Sinatra and the FBI
The FBI already built a case for Sinatra due to the draft-dodging allegations, so they decided to keep looking into him once they turned out to be false. Sinatra had a lot of questionable acquaintances such as Chicago gangster Sam Giancana, the Giacalone family, and Philadelphia gangster, Angelo Bruno.
Sinatra, knowing that the FBI was investigating him for his ties, offered himself up to be an informant in 1950 just to get them off of his back. The FBI ended up declining his offer but still kept tabs on him. Sinatra was also suspected of playing a part in the Red Scare that overtook Hollywood.