THE PRIVATE PLT AND 4 PAX WERE ATTEMPTING TAKEOFF ON RWY 13, A 3,900 X 30 FT ASPHALT RWY. THE PLT SAID THE ACFT ACCELERATED TO 100 KNOTS BUT HE COULD NOT RAISE THE NOSE FOR LIFT OFF. THE PLT SAID HE ABORTED THE TAKEOFF AND INTENTIONALLY GROUND LOOPED TO THE RT; HOWEVER, A WITNESS REPORTED THAT THE ACFT LEFT THE RWY AT HIGH SPEED AND THE ENGINES SOUNDED AS IF THEY WERE AT FULL POWER. A POST ACCIDENT INVESTIGATION BY AN FAA INVESTIGATOR REVEALED NO EVIDENCE OF PRE-ACCIDENT FAILURE OR MALFUNCTION. THE INVESTIGATOR SAID THAT THE GROUND IMPRESSIONS SHOWED NO INDICATION OF BRAKING AND INDICATED THE NOSE GEAR COLLAPSED 400 FEET BEYOND THE RWY. A SHORT DISTANCE FARTHER, THE MAIN GEAR COLLAPSED. THE ACFT CAME TO REST IN A DITCH, 900 FEET AFTER LEAVING THE RWY AND SLIGHTLY RIGHT OF THE EXTENDED RWY CENTER LINE. IN A POST ACC INTERVIEW CONCERNING THE CONTROLS POSSIBLY BEING LOCKED THE PLT STATED THAT THE CONTROL LOCK HAD BEEN MISSING FOR 'SEVERAL WEEKS.'