DEN89FA146

The plt depd julesburg, CO, btn 1830 & 1900 MDT. His original destn was casper, WY, but due to wx, he flew to billings, mt & lndd at abt 2200 MDT. At abt 2347, he took off with one pax on a flt to broomfield, CO. Bfr takeoff, he was adzd that cloud bases were at 9000' MSL; he replied they would not be flying that hi. While en route, the pax noted they wereat 7300'; the plt explained that would be abt 2800' to 3000' AGL. Later, the pax noted they were at 7500'; the plt said that would be abt 2400' AGL in that area. At abt 0200 MDT, the pax bcm sleepy & dozed; when she awoke, she believed the plt had dozed also. She nudged him & he straightened up, slapped his face & said he was fine. Later, the pax dozed again& awoke when the acft impacted the top of rising terrain (elevation aprx 7000'). Some 4 to 5 hrs ltr, when both regainedconsciousness, the pax asked the plt if he fell asleep. His response indcd to her that he had. The plt died at abt 0900.wx delayed a search. The acft was fnd in late afternoon after the ELT signal was rcvd by satellites & overflying acft.