At about 1930 CDT, the aircraft departed Yukon, OK on a direct flight to Alton, IL. It landed at Alton at about 2200 CDT, and about 10 minutes later, it departed on a return flight to Yukon. Before departing Alton, the pilot stated that he would refuel at Springfield, MO while on the return trip. However, there was no indication that the plane was refueled at Springfield. Subsequently, the aircraft crashed near Afton, OK at about 2350 CDT. A witness stated that he had seen the aircraft circling back and forth across the highway at low altitude, then it went into a left bank and nose dived into the ground. An investigation revealed the aircraft impacted in a near level attitude, but in a steep angle of descent. The fuel tanks were found to be empty. There was no evidence of fuel spillage on the ground, except near the right tip tank. The left and right fuel selectors were found positioned to the right main tank.