The man who stabbed Derek Chauvin in prison was 52-year-old John Turscak who previously worked as an FBI informant.How ironic. Chauvin was stabbed 22 times with a knife that was crafted by Turscak. This is where it gets interesting. Turscak was in prison after being found guilty of racketeering and conspiring to kill a gang rival. Before that, he worked as an FBI informant against the Mexican Mafia organization. When being sentenced in 2001, Turscak admitted that he carried out crimes while working undercover as an informant to the FBI. "I didn’t commit those crimes for kicks. I did them because I had to if I wanted to stay alive. I told that to the [FBI] agents and they just said, ‘Do what you have to do.’" (LA Times) Wild.