Contact an attorney who litigates in the area of civil rights. You don't have a day to waste. The surveillance videos that may have captured pieces of the story may not be stored for very long at all before being taped over, and an attorney can make the proper requests to preserve the evidence. The lawyer will want to know exactly which facility this occurred at and when. A law enforcement agency should investigate this, but not necessarily the one providing corrections officers at that facility. If it is a state facility, my inclination would be to contact the FBI. The communications between the inmate and you have probably been recorded. If your friend is inventing part of this story, that would be very serious. If you can't find a civil rights attorney, try getting a recommendation for a lawyer who might handle it from someone at the local public defender office, or call the attorney who originally represented him. That lawyer might be able to arrange a quick attorney/client call or visit with the inmate without delay and without danger of being recorded. Good luck.