On May 22, 1993, at 0845 mountain daylight time, a Beech 60, N620E, experienced a complete landing gear collapse during the landing roll at the Bullfrog Airstrip, Bullfrog, Utah. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the certificated private pilot and his three passengers were not injured. The flight had departed from Salt Lake City, Utah, on May 22, 1993, at 0745, as a pleasure flight. The pilot reported that while on final approach, he checked that the landing gear was in the down and locked position. After a normal touch down, the airplane rolled approximately 350 feet when the nose gear collapsed. The left main landing gear then collapsed, and a short time later when the airplane veered to the left, the right main landing gear collapsed. Measurements of the damage to the runway were taken by the United States Department of the Interior, National Park Service. The first impact mark was measured at 306 feet from the end of the runway, where a skid mark was visible for a distance of 26 feet. Propeller impact marks were visible from 332 feet to approximately 400 feet on both sides of the runway centerline. Skid marks from the nose gear were noticed down the center. One of these marks was straight, then it turned to the right approximately 45 degrees. Marks after that point skipped as if the nose gear was turned laterally and hopping. At 367 feet to 450 feet, metal transfer marks were visible travelling from the last skid marks from the nose gear. At 470 feet, metal and fiberglass transfer marks were visible on the left side of the center line where the left main landing gear collapsed and the engine nacelle drug along the surface. These marks continue to the airplane resting point, 1,230 feet from the end of the runway. Rubber skid marks from the right main landing gear start at 527 feet and continue to the final resting point of the airplane. After the airplane was retrieved and moved to Salt Lake City, a certificated mechanic and an inspector from the Salt Lake City Flight Standards District Office examined the landing gear. It was found that the cam casting that turns the nose gear into the wheel well was broken. There was no visual evidence of a pre existing failure. The retract rods on the main landing gear were bent.