Law enforcement officials have said they were told by witnesses that Wells was not on the boat when it left the island. Speaking at the National Urban League Conference on Thursday, the civil rights attorney Ben Crump said Wells’ family had retained audio engineering experts to review the recording. A day after the discovery, Jackson County Sheriff John Ledbetter said Wells’ friends were cooperating with authorities and that investigators did not suspect foul play. An independent autopsy commissioned by Wells’ family was inconclusive about the cause of his death. Some have made unsubstantiated claims against Wells’ friends, whose attorneys and family members have since reported death threats and doxing campaigns.