The official position of the United States Government is Marine Corps Colonel James E. Sabow committed suicide. He allegedly died by an intraoral shotgun discharge in the backyard of his quarters on the El Toro Marine Corps Air Station, Orange County, California, USA in 1991. However, questions have persisted since the Colonel’s death whether he died by homicide. The two scenarios on the manner of death, suicide and homicide, were evaluated as to the gunshot residue (GSR) and back spatter residue (BSR) on the Colonel’s clothing, the bloodstains on and off the body and the position of the body at the death scene. The shotgun, when test fired, was shown to leak GSR from its breech and trigger housing. Samples from the Colonel’s clothing were analysed by scanning electron microscopy/energy dispersive X-ray analysis show there are no concentrations of GSR or BSR on the clothing that should be present if the Colonel committed suicide. Bloodstains on and away from the body and the position of the body do not support the suicide scenario, The Colonel’s body was staged to appear he committed suicide. There is no evidence of suicide. The Colonel’s death was a homicide.