On March 23, 1998, about 1025 hours Pacific standard time, a Beech C35, N8489A, was substantially damaged during an off-airport landing near Rio Linda, California. The solo private pilot, operating under the provisions of 14 CFR Part 91, was not injured. Visual meteorological conditions prevailed for the personal flight and no flight plan was filed. The practice flight originated at Rio Linda approximately 1000; performed two landings in Lincoln, California, and was returning to Rio Linda. A Federal Aviation Administration inspector from the Sacramento, California, Flight Standards District Office examined the wreckage on-scene. In his statement, he reported the left wing was found severed from the fuselage and lying inverted, and the fuel tank was split open with only a slight hint of fuel and no evidence of a fuel spill on the ground. The right wing fuel tank was opened and no fuel could be seen in the tank. The right wing tank sump drain was opened and nothing came out. There was only a hint of fuel at the fuel strainer drain. The fuel selector was found in the right fuel tank detent. The pilot stated that the aircraft was inside a locked hangar when he performed his preflight check. He said the only light available was the one coming through the skylight. During his visual check of the fuel levels, it appeared from light reflection that the fuel was all the way to the tank openings.