The airplane landed with the landing gear retracted and it veered off the runway. The airplane collided with a ditch, resulting in substantial damage to the fuselage and the right wing rear spar. Examination of the runway revealed numerous gouges on the runway surface, beginning on the centerline 1,999 feet from the approach end of the runway and continuing for 843 feet, which were consistent with a propeller strike. An examination of the airplane revealed that all three landing gear doors were found in the retracted position. The landing gear doors and the tip tanks displayed evidence of scrape marks as well. An examination of the tires revealed that all of the tires were inflated. An examination of the cockpit revealed that the landing gear handle was in the "gear up" position. The airplane was placed on jacks, and the battery switch was turned to the "on" position. The landing gear horn was operational, and all three landing gear lights were not illuminated. The gear was manually extended, and the gear horn silenced and all three landing gear position lights illuminated green.