SILVER CITY, N.M. (AP) -- More search teams fanned out in the rugged wilderness of New Mexico's Gila National Forest Saturday as the search expanded for renowned long-distance runner Micah True, who has not been seen since heading out for a run four days earlier.
Authorities say 60-year-old True, of Boulder, Colo., left for a run Tuesday morning from a lodge and didn't return. A search began on Wednesday.
True is an accomplished extreme-distance ultrarunner -- taking on distances of 50 miles or more -- who was featured in the bestselling book "Born to Run."
There's added concern because temperatures have dipped into the mid-20s on some recent nights and true was last seen wearing only shorts and a T-shirt and carrying a water bottle.
The 14 search teams that were scouring the area on Friday were supplemented with additional volunteer teams from across the state Saturday morning, said New Mexico state police spokesman Lt. Robert McDonald. Teams were on horseback, using dogs and a helicopter and search plane were being used.
Still, as the days pass, the chances of a successful rescue diminish.
"We're going to do everything possible to cover as much ground as possible, but it's already been four days," McDonald said. "By no means are we going to give up, but time is of the essence as always in a search and rescue effort."
True is the race director of The Copper Canyon Ultra Marathon, a 50-plus mile extreme race that took place in Urique, Mexico on March 4 and has been featured in the magazines "Running Times" and "Outside," according to the Silver City Daily Press. He was the central character -- known as "Caballo Blanco" -- in "Born to Run," a non-fiction book by Christopher McDougall.
He was staying at The Wilderness Lodge and Hot Springs near the Gila Cliff Dwellings in southwestern New Mexico.
When True hadn't returned by Wednesday morning, Jane and Dean Brummer, co-owners of the lodge, contacted State Police and the search launched. Dean Brummer helped in the search.
"He left his car and dog here and he ran up the road to where the trailheads are," Dean Brummer told the paper. "So they don't know which trail he would have taken. He didn't tell anybody where he was going and it's a pretty big wilderness out there. We've looked in all the obvious places, and a lot of the not-so obvious."