BANGKOK, Aug 4 (AFP) – An American found dead in a central Bangkok hotel room with a plastic bag covering his head was believed to have been murdered, police said this morning. Wayne Tischbern, 58, was found yesterday when hotel staff informed police that he had spent an unusually long time in his room. Tischbern was handcuffed, there was tape tied around his neck, and his head was covered with a plastic bag. A police doctor said suffocation was the cause of death.