CHEYENNE -- Bobby Model, a noted adventure photographer who suffered a traumatic brain injury more than two years ago in South Africa when a chunk of concrete smashed through the windshield of his car, has died. He was 36.

Model died Wednesday at West Park Hospital in Cody after a brief illness, said Sharon Miller, Model's photo assistant. The cause of death of wasn't immediately available.

Model's work appeared in National Geographic, Outside, The New York Times and other publications. His assignments took him from the rivers of Burundi in search of a fabled man-eating crocodile to climbing the Nameless Tower of northern Pakistan, one of the world's largest granite walls.

"He really was a guy that lived his life," said Steve Bechtel of Lander, a fellow rock climber and Model's roommate at the University of Wyoming. "I don't think he had a lot of regrets. He pretty much thought of the things he wanted to do, figured out how to make it happen, and then implemented his plans. That's a really cool thing that not many of us get to do."

Model moved to Nairobi, Kenya, in 2004 to better position himself to cover Africa, according to a biography on his Web site. Model's sister, Faith Model, shared a house with her brother in Nairobi. She was driving Bobby to meet some friends when the incident happened in Cape Town, South Africa, in June 2007.

Police opened an investigation but suspended the case when it went cold.

Anne Young, Bobby's mother, said it was a mysterious tragedy.

"You wonder why this happened. Was it a carjacking? Was it someone trying to feed a starving kid and were desperate?" Young said in an interview with The Associated Press in March 2008. "Maybe it was just a random act -- wrong place at the wrong time. We don't know."

Model underwent treatment in South Africa, New York and Denver before returning to his hometown of Cody in December.

Miller said Thursday that Model's rapid decline this week was a shock.

"I think he was just working hard, trying to stay positive," she said. "He had a lot of therapies -- actively working on speech therapy, physical therapy, occupational therapy -- the whole bit. It's such a traumatic injury, it just requires huge amounts of efforts to get back."

Tim Power, Park County coroner and owner of Ballard Funeral Home in Cody, said arrangements for Model were pending as of Thursday.

Model landed his first major photography assignment in 1995 when he accompanied renowned rock climber Todd Skinner to the Nameless Tower in northern Pakistan. National Geographic helped fund the journey, on which Model shot memorable images of the granite spire.

In 2006, Model was named a National Geographic Society "Emerging Explorer" because he "braves the most challenging locations to cover the toughest topics -- culture, conflict and extreme adventure."

Model was working on a National Geographic photo essay documenting the Baltistan region of Pakistan, site of a border dispute with India, around the time of his injury. He viewed the assignment as a chance to branch out from adventure photography.

Rebecca Martin, director of the expeditions council at National Geographic, frequently called on Model for adventure assignments.

"You could send him off anywhere and he'd come back with an incredible story," Martin told The Associated Press in March 2008.

Bechtel said Model's health had been improving amid the challenges of therapy.

"It was a strange situation with him because it was so much stress for so long, and it seemed like we just started catching our breath before this happened," Bechtel said Thursday.

"Bobby was a good communicator and a compassionate person," Bechtel added. "He's one of those ones that the world is worse off without."