The pilot reported, that while departing from the runway the right cockpit door opened. The pilot was unable to close the door and he decided to return to the airport to close the door on the ground. While on final approach and near the runway, the pilot thought he heard the stall warning horn, so he immediately flared the airplane to land. The airplane bounced twice on the runway, so the pilot attempted to abort the landing by advancing the throttle. The airplane veered to the left, exited the runway, and the pilot reduced the throttle in an attempt to maintain directional control. The airplane then struck the runway’s precision approach path indicator before coming to rest in a ditch. The airplane’s firewall was substantially damaged. Following the accident, the pilot stated, “In hindsight I don't think the sound I heard was the stall warning horn, but rather the sound squealing through the partially open door which confused me into thinking the aircraft had stalled.” Given this information, it is likely that the pilot was distracted by the open right door during the landing, which contributed to his loss of control during the landing attempt. A Federal Aviation Administration inspector examined the airplane after the accident reported that she did not observe evidence of any preaccident mechanical malfunction or failure of the airplane that would have precluded normal operation, and specifically that there were no mechanical issues with the airplane’s right door latch. Given this information, it is also likely that the pilot had failed to ensure that the door was properly secured prior to departing on the accident flight.