Apparently you can serve two masters.
In Montreal, QB Canada Marvin Elkind was a small-time Jewish hood working for the Italian Mafia who later became a police informant, and the 77-year-old's double life is the subject of the new book The Weasel by Adrian Humphreys as reported by Rene Bruemmer for The Gazette.
Elkind got his underworld start at the age of 18 as the driver for Jimmy Hoffa whom he chauffeured for four years, and he claims to know where the infamous Teamsters boss is buried as reported by Joe O'Connor for the National Post: "' have it on good authority that Mr. Jimmy Hoffa is resting at the Renaissance Center Hotel, in the concrete, in Detroit, Michigan,' says Marvin Elkind."
He "forged ties with some of the most notorious gangsters in Canada and the United States," and then flipped where for "25 years he worked for the OPP [Ontario Provincial Police] as well as the FBI, U.S. Customs, Scotland Yard and RCMP, helping cops get close to some nasty criminals" including Johnny "Pops" Papalia "who was gunned down in Hamilton, in a hired hit outside his Railway Street office in 1997" as reported by Susan Clairmont for The Spectator: "'He did the world a favour by not being alive today,' says The Weasel. 'Johnny was a very bad person. Pure evil. Liked to hurt people. He didn't like me, but he trusted me.'"