The non-instrument rated pilot was on a night, VFR, return flight, when the airplane struck high terrain about 1.5 mile from the destination airport and about 500 feet above the airport elevation. A witness, who saw the flight depart the airport VFR about three hours earlier, reported the weather at the airport was foggy with zero visibility at about the time of the accident. The same witness stated the fog began to occur at the airport about 45 minutes after the earlier departure. The witness also reported the runway lights were on, but the airport rotating beacon was not operating. The pilot had received radar vectors to the airport. He requested and was given confirmation from the air traffic controller that he was over the airport. An examination of the airplane did not disclose evidence of mechanical malfunction. About 25 miles east-northeast at Bluefield, WV, the weather was in part: 100' obscuration, visibility 1/16 mile with fog, wind calm.