ALBUQUERQUE, N.M. (AP) -- Up mountainsides, through deserts and the wildest of rugged terrain, there was little that could break the serenity or solitude of Micah True as he ran. Only, perhaps, the pounding beat of his heart or the rhythm of his feet as they hit the trail, mile after mile after mile.
For True, running -- the pure act of traveling relentlessly long distances -- was a passion that needed no justification. To those who knew him well, it also brought forth an intense playfulness in the 58-year-old ultra-marathon runner.
"When he was out on the trail running, it was like someone just rang the school bell and said, 'Recess.' It was utter playfulness," recalled Chris McDougall, a friend of True's and author of the nonfiction best-seller "Born to Run."
True's body was discovered Saturday evening in a remote part of southern New Mexico's Gila Wilderness. The search began for him days earlier after he failed to return Tuesday from a 12-mile run.
He was found near a cold stream, his legs still in the water and his water bottle next to him, about a mile southeast of the Gila Cliff Dwellings.
The cause of death wasn't known Sunday. There were no obvious signs of trauma, and State Police Lt. Robert McDonald said it could take a couple of days before authorities know what happened.
But word of his death spread immediately through the community of runners, both amateur and accomplished, some of whom view True as an inspiration, a reason they took up the sport.
Friends and admirers also posted condolences and shared fond memories on social networking sites of a man who, by nearly all of those accounts, was a truly memorable person.
Barry Anderson, a manager at Runner's Den in Phoenix, said the sport would greatly miss True.
"He was both an international running celebrity, and the first person to smile and shake your hand when you crossed the finish line behind him," Anderson wrote in a posting on Runner's Den Facebook page. "The fact that so many people from all over the country dropped everything and immediately went to his aid is testimony to the way he lived his life and the way he himself treated his friends."
Many on Sunday described True in the most reverential and laudatory of terms, with "legendary" and "inspirational" chief among them.
Brian Metzler, who lives in Boulder, Colo., and edits the running magazine "Competitor," had known True for about 12 years. He described True as "very real and very pure of heart" and someone who liked to "go out there and connect with the earth and connect with the world."
"He was in it for spreading that gospel, spreading that joy of running," Metzler said.
True was the race director of The Copper Canyon Ultra Marathon, a 50-plus mile extreme race that took place in Urique, Mexico. This year's race marked a record turnout with hundreds of runners, most of them local Tarahumara, or Raramuri, Indians who are known for their extreme running. The prize money and corn vouchers awarded to finishers were all aimed at helping the Tarahumara.
True was featured in articles in running magazines and was a central character -- known by his nickname, "Caballo Blanco" -- in McDougall's "Born to Run."
McDougall, who left New Mexico on Sunday after helping with the search, based his book on the first Copper Canyon run that True organized in 2003.
Without True, McDougall said he's not sure whether the Copper Canyon race will be able to continue. The Tarahumara are extraordinarily reclusive and True was able to build a relationship with them based on trust and confidence, he said.
"He is the only person, I think, in our lifetime who has done a great job of very respectfully bringing awareness of that tradition to the rest of the world and creating a race that is a celebration of who they are."
A trail guide for hire, True spent his time traveling between Copper Canyon and Boulder, making stops now and then in New Mexico and Arizona.
Last Tuesday, True had a few hours to spare before leaving The Wilderness Lodge and Hot Springs, where he often stayed while in New Mexico. After eating breakfast, he set off on what would have been a routine 12-mile run. He had run six miles the day before.
He left his dog at the lodge but never returned.
Dozens of searchers combed the rugged wilderness looking for him. Two of the best ultra-runners in the U.S. -- Scott Jurek and Kyle Skaggs -- joined McDougall and others who gathered from around the country to help.
McDougall, in a Twitter message sent late Saturday, said: "Caballo had the only funeral he would have wanted: his friends spent days running in the wilderness in his honor."
Because True knew the area and wasn't one for trying new trails without being shown around, McDougall said they all hoped that he would walk out of the woods with "that goofy grin" on his face.
True's smile was recognizable by runners around the country.
Mark Cosmas, owner of iRun in Phoenix, said True was all about living life and helping other people enjoy running.
"He might not have been the fastest or the most talented, but the joy and the passion that he brought to the ultra-running community was just infectious," Cosmas said.
Some found solace in the fact that True died doing what he loved most -- what he did most every day of his life.
To grasp the importance of running to True and a glimpse of that playfulness all his friends talked about, look no further than the short greeting on his voice mail: "Chances are I'm either running up a mountain, or I'm drinking a cerveza ..."
Associated Press reporters Bob Christie in Phoenix and Thomas Peipert in Denver contributed.