On July 26, 1997, at 1730 mountain daylight time, a Beech D50A, N3BE, was substantially damaged during a forced landing near Mitchell, Nebraska. The pilot reported that one engine lost power during cruise. He was not injured. The 14 CFR Part 91 flight had departed Torrington, Wyoming, at 1715, with a planned destination of Scottsbluff, Nebraska. Visual meteorological conditions prevailed and no flight plan was filed. After sitting for two years at Torrington, Wyoming, the aircraft was prepared by the pilot for a flight to Scottsbluff, Nebraska. The pilot had 25 gallons of fuel put into each side of the aircraft. The pilot said he "was talking to the airport manager while the aircraft was being fueled." The fueler reported that the pilot removed the outboard fuel caps and he filled those tanks. The pilot then replaced the fuel caps after fueling was completed. The pilot stated he "failed to recheck fueling and individual tanks." The main tanks for this aircraft are on the inboard side of the engine nacelles. The outboard tanks are the auxiliary tanks. The pilot said "fuel had been placed in aux. tanks, which are filled outboard of engine nacelles. Main tanks are inboard. Thinking he had put 25 gallons in main tanks, I departed." The pilot said that he did some taxi tests and partial power runs down the runway. A witness at the airport said the aircraft taxied for a short time, 10 to 15 minutes and did one partial power run down the runway. The pilot said he "then shut down the engines, checked for leaks, found none and departed." The airplane departed the airport with the pilot reporting "roll, climb and cruise were normal." After leveling at 6,000' mean sea level/1,500' above ground level and 10 minutes en route, the left engine lost "75 percent of its power." The pilot reported going through the normal checks. He reported that he switched to the auxiliary tank and "the engine came back momentarily, then quit." The pilot reported he switched back to the main tank and prepared for landing. The pilot said the right engine was running ok. The pilot reported he put the gear down and landed in a rough field. The right main gear and nose gear came off, and the fuselage wrinkled behind the cockpit. The reported that when he examined the airplane after the accident he found the left main tank to be "bone dry." He reported that the power loss was a result of fuel starvation.