The 21-year-old student's death, discovered early Monday, immediately ignited strong emotions in a Southern state with a history of racist violence.
Even before the autopsy results were announced, the student's family and their lawyers had called for an independent autopsy and implored police to show them any security camera recordings and other video gathered as evidence. Civil rights attorney Ben Crump has said he will lead an independent investigation.
Crump's office did not immediately return an email message seeking comment Thursday.
Cleveland police released no details of the autopsy's findings other than to say the cause of death was hanging and the manner of death had been ruled a suicide. It said results of toxicology tests are still pending and could take weeks.
The statement said police are still investigating the student's death and that evidentiary files in the case are being shared with the FBI and federal prosecutors.
U.S. Rep. Bennie Thompson, a Mississippi Democrat, had previously called on the FBI to investigate.