On June 12, 2007, about 1530 Pacific daylight time, a Cessna 340A, N340WS, experienced a dual loss of engine power and sustained substantial damage during the ensuing forced landing in the desert near Ludlow, California. The private pilot, the sole occupant, received minor injuries. The airplane was registered to and operated by the pilot under 14 CFR Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the personal cross country flight from Bullhead City, Arizona, to Ontario, California. The flight departed Laughlin/Bullhead City International Airport about 30 minutes prior to the accident. During a telephone interview conducted by the NTSB investigator-in-charge and in a written statement, the pilot reported he landed at Bullhead City on June 9 and had the airplane refueled with 74.6 gallons of 100LL, which filled the main and auxiliary fuel tanks. The pilot stated that he did not visually inspect the fuel level in the tanks before departure. About 15 minutes into the flight, he noticed that the fuel gages were "erratic." About 5 minutes later, the left engine lost power and then regained power with no action by the pilot. Shortly thereafter, the right engine lost power, and the pilot "went to aux pumps" and attempted a restart with no success. The left engine then lost power for the second time, and the pilot "went to aux pumps" and attempted a restart with no success. The pilot made a forced landing in the desert alongside Interstate 40. During the landing roll, the airplane struck rocks. Damage to the airplane included a bent and buckled left wing, puncture of the left wing tip (main) tank, collapsed landing gear, and deformation of the fuselage bottom. Examination of the airplane at the accident site by an FAA inspector revealed that the right main tank was intact and contained no fuel, and the left main tank was punctured and contained a trace of fuel. Both auxiliary tanks contained fuel. When drained by recovery personnel, the right auxiliary tank yielded 27 gallons of fuel and the left auxiliary tank yielded 21 gallons of fuel. The FAA inspector reported that both the left and right fuel selectors were positioned to the right main tank, and the auxiliary fuel pump switches were both in the low position. Review of the Pilot's Operating Handbook for the Cessna 340A indicated that in order to utilize the fuel in the auxiliary tanks, the left and right fuel selectors must be positioned to the left and right auxiliary tanks, respectively, and the auxiliary fuel pump switches should be placed in the low position. When questioned about the amount of fuel on board the airplane at departure from Bullhead City, the pilot stated that he believed fuel must have been stolen from the airplane while it was parked on the ramp between June 9 and June 12. A written statement was obtained from the line service technician who refueled the airplane, which confirmed that he topped off the airplane with 74.6 gallons of 100LL about 1930 on June 9.