South Wales Police said the tragedy was being investigated by the Police Complaints Authority and the Swansea coroner Richard Morgan.
A Home Office pathologist was also called to the scene and was carrying out a post mortem examination yesterday.
The Welsh force refused to give details about the circumstances of David's death or why he was being held in custody.
Yesterday his parents Tony and June were being comforted by relatives at their home in Penlan, Swansea, just two miles from the police station where he died. A family spokesman said: "Everyone is very distressed ... We are still waiting to find out exactly what happened."Reuse content