On October 14, 2002, at approximately 1520 mountain daylight time, a Mooney M20J, N8084D, was substantially damaged when the landing gear collapsed during landing roll at Centennial Airport, Englewood, Colorado. The private pilot and his passenger were not injured. The pilot/owner was operating the airplane under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal cross-country flight that originated from Montrose, Colorado, approximately 2 hours before the accident. No flight plan had been filed. The pilot said that when he put the landing gear down everything "sounded and felt normal," but he had an unsafe gear indication. He made a pass over the airport, and tower personnel indicated that all three landing gear appeared to be down and locked. The pilot requested that a mechanic (familiar with Mooney aircraft) watch him fly-by and give him his opinion on the landing gear problem. The mechanic said that "everything looked great and that ninety five percent of the time, the problem was an indicator problem, not an actual mechanical failure. Although the unsafe light was still illuminated, the pilot decided to land. During the landing roll, the gear collapsed and the airplane exited the south side of runway 28 into the dirt. The bulkhead at station 53 was bent, and the prop and engine were also damaged. According to the pilot's accident report, the reason for the collapse of the landing gear had not been determined.