The airplane sustained substantial damage when it impacted terrain while maneuvering at approximately 1215 Central time, killing the Private pilot and two passengers. Visual conditions prevailed. A pilot-rated witness reported seeing the airplane on final approach with its landing gear retracted. He then observed the airplane make a shallow left turn, followed by a second left turn, but with a 60-70 degree bank angle. The witness stated that during the second turn the airplane did a knife-edge drop. Before losing sight of the airplane behind a row of hangars, it appeared that the airplane was leveling off. The airplane came to rest upright in the backyard of a residential area. All components of the airplane were accounted for at the accident site.