As the airplane was approaching the (flight planned) destination at night, the pilot indicated he would land from a visual approach. He canceled his IFR flight plan about 5 miles west southwest of the airport and began a descent. Radar data was lost as the airplane passed south of the airport on an east southeasterly heading and had descended to about 3000 ft MSL. It collided with rising terrain at an elevation of about 3000 ft, after traveling an additional 3 1/2 miles. The crash site was about 8 miles south southeast of the airport. The wreckage was strewn over a distance of about 512 ft through trees on a heading of 122 degrees. A post accident examination revealed that the flaps were fully retracted and the gear was stowed. No airframe or engine anomalies were noted. All of the propeller blades exhibited torsional damage. A pathological exam of the pilot did not reveal any medical problem that would have caused the accident. Light snow was falling and low clouds were in the area.