FBI agent Francis O'Neill Jr. and his partner James Sibert were present at the autopsy on behalf of the FBI. They wrote a report of the autopsy on which the FBI report was based, and which is at odds with the autopsy report given the Warren Commission. Sibert and O'Neill were privately interviewed by staffers of the Warren Commission and HSCA, but testified before neither body.

This ARRB deposition covers several areas, including Sibert and O'Neill's treatment by the Warren Commission's Arlen Specter, the FBI pair's arrival at and witnessing of the autopsy, their later reporting on it, and general observations, including reaction to the autopsy photographs and X-rays. O'Neill told the ARRB that the photographs of the back of the head looked to have been "doctored," and that the brain photographs didn't match his recollection. "It looks like a complete brain," O'Neill remarked upon seeing the photographs.