On January 18, 2001, about 1500 central standard time, a Cessna 150G, N6281S, piloted by a private pilot, sustained substantial damage during nose over encountered on a forced landing to a snow covered field, following an in-flight loss of engine power near La Rose, Illinois. The personal flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. The pilot reported no injuries. The flight departed from Illinois Valley Regional-Walter A. Duncan Field Airport, near Peru, Illinois, about 1440 and was returning to Marshall County Airport at the time of the accident. The pilot stated, "In order to describe the circumstances leading up to this accident in chronological order we have to go back to the ending of my last flight. I have been flying this aircraft for the past nineteen years and the ending of every flight was a stop at the fuel pumps to top up the tanks." The pilot did not state that he looked in the fuel tanks during the airplane's preflight for the accident flight. He stated that he perceived that the fuel gauges indicated full. He said, "They are always full. ... My conclusion - Someone between my last flight and this, someone entered my hanger and removed 76% (17 gals) of the useable fuel from my airplane. I do not say this as an excuse. There is no excuse for running out of fuel. The regulations are quite plain as to who is responsible to insure adequate fuel for the flight. That's fine. I can live with that. I've always been willing to accept the responsibility for my actions. ... As for the future, if I choose to continue pursuing this hobby, my check list will have to include two more lines, 'Stick the tanks' and 'Check for theft and vandalism!'." The Federal Aviation Administration arranged for a Fixed Base Operator to perform an examination of the airplane. The airplane's engine was test run at low power and it ran smoothly. Fuel was put in each tank and the fuel gauges indicated above empty. Fuel was found leaking from around the shaft of the fuel shut off valve.