The airplane impacted mountainous terrain while maneuvering at approximately 1530 Mountain time. The Commercial pilot and two of the three passengers were killed; the other passenger received serious injuries. Visual conditions prevailed. At the time of the accident, a motorglider was flying near where the accident occurred. The motorglider pilot and the accident-aircraft pilot coordinated a rendezvous away from the departure airport. Subsequently, the accident airplane made one pass above the glider, then circled and made a second pass above and to the left of the glider. The glider pilot then watched the airplane continue heading north straight out in front of him for about 5 to 10 seconds. Since the glider was losing lift, he then made a turn to the south. After gaining altitude, the glider pilot turned back to the north. He then saw a column of black smoke, which was later identified as being from the crash site. The column of smoke was located just south of the 8800-foot peak on the transverse ridge. The glider pilot estimated it was 5 to 10 minutes between the time he last saw the airplane and the time he turned back north and spotted the smoke. The glider pilot reported that the weather was clear blue sky, no turbulence, no sucking downdrafts, but some down air in the area where he last saw the airplane.