A Chicago Police detective allegedly tortured an inmate in the U.S. prison at Guantanamo Bay while he moonlighted in his position as a Navy reserve lieutenant, according to a story published Wednesday in the Guardian newspaper.

Richard Zuley, who retired from the department and now works for the city’s Aviation Department, took over the interrogation of Mohamedou Ould Slahi at Guantanamo in 2002, the newspaper reported.

Zuley’s interrogation plan received “a personal signoff” from then-U.S. Defense Secretary Donald Rumsfeld, the Guardian reported. Mark Fallon, deputy commander of the former Criminal Investigative Task Force at Guantanamo, was quoted as saying Zuley’s interrogation of Slahi was “illegal” and “immoral.”

Slahi is suspected of helping and recruiting three of the 9/11 hijackers. He is one of the longest-held prisoners at Guantanamo Bay. His memoir, “Guantanamo Diaries,” was published in January and claims he was beaten and subjected to a mock execution and death threats.

Court records show Zuley also is a defendant in a wrongful-conviction lawsuit Lathierial Boyd brought against the city of Chicago in U.S. District Court here. In 2013, Boyd’s murder conviction was vacated in a fatal shooting outside Wrigley Field two decades ago. Boyd accuses Zuley of being among the officers who allegedly framed him for the killing.

The Guardian said Zuley did not respond to requests for comment.