At 0710 Central time, the airplane was substantially damaged when it impacted terrain during a forced landing following a loss of engine power. The Airline Transport pilot and three occupants of the airplane were uninjured. Visual conditions prevailed. The business flight was originating at the time of the accident. The pilot later reported that the engine lost oil pressure and seized during climb-out. The airplane was substantially damaged during the forced landing in a field approximately four miles east of the departure airport. The FAA inspector reported that he did not see any evidence of oil on the engine oil dipstick. He added that the oil cap was secured in place.