THE ACFT WAS ON THE LAST LEG OF A SCHEDULED COMMUTER FLIGHT, WHEN IT CRASHED IN A HEAVILY WOODED AREA WHILE MAKING A VFR APPROACH TO MERRILL FIELD, ANCHORAGE, AK. THE CAPT AND HIS SOLE PASSENGER WERE KILLED IN THE CRASH WHEN THE AIRPLANE STRUCK THE GROUND UPSIDE-DOWN IN A NEAR VERTICAL ATTITUDE. THE AIRPLANE'S COPILOT, WHO HAD DEPLANED MINUTES BEFORE THE ACCIDENT FLIGHT, SAID HE DID NOT SEE THE CAPT USE THE AIRCRAFT'S AUXILIARY FUEL TANKS AT ANY TIME DURING THAT EVENING'S EARLIER FLIGHTS. THE AIRPLANE'S MAIN FUEL TANKS HOLD 100 GALLONS OF USEABLE FUEL; IT IS ESTIMATED THAT THE AIRPLANE WOULD HAVE CONSUMED SLIGHTLY MORE THAN 100 GALLONS OF FUEL AT THE TIME OF THE ACCIDENT. AMPLE FUEL REMAINED IN THE AUXILIARY TANKS, BUT AN ENGINE RESTART CANNOT BE READILY ACCOMPLISHED IF THE AUXILIARY TANKS ARE NOT SELECTED PRIOR TO THE ENGINE'S QUITTING.