Federal authorities have used witness videos and a tattoo to track down a man in a “Joker” mask who allegedly set fire to a police car during anti-police brutality protests in Chicago on May 30. Timothy O’Donnell was captured on video holding a lit object and putting it in the car’s gas tank, according to court documents obtained by a Chicago Sun Times reporter. Photos contained in the court documents show that O’Donnell was partly identified by a tattoo on his neck that says, “PRETTY.” When cops raided his home, they found the mask and O’Donnell allegedly admitted that he was the masked person in the videos. Protests in Chicago have been marred by looting, fires and property destruction.