Witness Account
A witness reported seeing the airplane circling low overhead in a clockwise to rectangular pattern. The witness observed the airplane turning southerly and descending, when it pitched up 45 degrees and appeared to stall. The airplane then entered a 45-degree dive. The witness stated that the airplane sounded normal throughout the event.
Investigation Findings
Local police searched the hangar for signs of a suicide note after the pilot's wife reported that the pilot had recently been acting despondent. No such note was found. During the investigation, no mechanical failure or malfunction of the airframe, powerplant, or flight controls was discovered.
Conclusion
No probable cause has been determined from the available information. The investigation did not find evidence of mechanical issues, and the witness account describes a stall and dive but does not indicate any abnormalities in engine sound.