The FBI has opened an investigation into possible drug trafficking and corruption at Clinton Correctional Facility, according to several reports. The probe comes out of ongoing investigations into the prison break three weeks ago that triggered a massive manhunt and ended this weekend with inmate Richard Matt shot dead, and David Sweat shot and captured. So far, prison workers have told federal agents about heroin use among prisoners, and prison staff's involvement in moving drugs, CNN reported.

The feds are looking into whether Matt and Sweat got special treatment for involvement in a prisoner-guard drug ring, and whether that eased their escape, the cable news channel wrote. They also believe that the two spent a year chatting up guards as a way of gathering information about the locations of nearby hunting cabins. Asked by a New York Times reporter whether there is a new drug and corruption investigation, an FBI spokesman said he could neither confirm nor deny it.

The FBI is in some ways redoing the work of state investigators assigned to the prison break, re-interviewing the same workers and inmates. An anonymous source told the New York Post that the new federal inquiry is "a vote of no confidence by the feds in the state investigation."