BRAWLEY, Calif. — Ultimate Fighting Championship star Evan Tanner has died in the desert east of San Diego, possibly of heat exposure.

Sheriff's Lt. George Moreno says the 37-year-old Tanner was found Monday about two miles from his campsite in a remote area of the Palo Verdes Mountains, where temperatures had reached 110 degrees. Moreno says a preliminary coroner's report suggests Tanner died of heat exposure.

Tanner left for the desert last week to go camping and motorcycle riding.

His agent, John Hayner, says Tanner called a friend on Wednesday to say the dirt bike had run out of gas. He was about 100 miles from the nearest town.

Tanner had planned to take a trip to the desert since last month. On his weblog on Spike.com, Tanner described his fascination with the emptiness of the desert and preparations for the trip.

"I plan on going so deep into the desert, that any failure of my equipment, could cost me my life," he wrote on Aug. 16.

Sheriff's officials said family members kept in touch with Tanner with text messages since he left on Wednesday, and became concerned when he stopped responding.

Crews have been searching for Tanner since Friday.

Tanner's agent, John Hayner, said his client led a simple life and always had an appreciation for the outdoors.

"He was always planning on going on some sort of adventure," Hayner told UFC.com. "And he never needed the finer things or made a fuss about them. He just needed enough for gas, shelter, and training."

Tanner's MMA record was 32-8. He began competing in the sport in 1997, winning a one-night tournament as part of his debut. Perhaps his greatest moment in the sport came at UFC 51, when he defeated David Terrell to become middleweight champion.

He lost the championship to Rich Franklin at UFC 53.

His final MMA bout was a split-decision loss to Maui's Kendall Grove at The Ultimate Fighter 7 Finale on June 21.