The aircraft had been fully serviced with fuel (48 gal usable supply) and had been flown 1.8 hrs prior to this flight. Reportedly, the pilot had relied on his fuel log and fuel gauges, and did not visually check the fuel quantity during the preflight. While on a gradual descent toward the airport, the engine lost power and would not restart. A crash landing was made in plowed field about 1/2 mi from the airport. No fuel was found in the fuel tanks and lines. The aircraft had flown .6 hrs on this flight or 2.4 hrs since it was refueled. At 75% power, about 24 gal would have been consumed. Red fuel stains were found on the inlet fuel line and on the fire wall below the line. With the cowling on, the pilot would not have been able to observe the stains. The fuel line (PN S1236-8-0280) was removed and pressure checked at 7 psi. During the check, a small stream of fuel about 1/16 inch in diameter was noted. Also, fuel thefts had been reported at the airport.