This story first aired on 11/12/2015.

Micah True was a loner by most accounts, happy to run long distances each day and live on his own in the canyons of Northern Mexico. Not even his neighbors knew exactly where he lived. But True also loved people -- in particular, the Raramuri people who called those canyons home. He first met a few of them when they ran the 1993 Leadville 100 Trail Run.

Scott Jurek, left, and Arnulfo Quimare running in Northern Mexico. They competed in the 2006 race set up by Micah True. Quimare won the race and Jurek got second place.

(Luis Escobar)

They inspired him to leave his home in Colorado and move south. Then, in 2006, True founded a race through the canyons to benefit the Raramuri, who's name means "foot runner" in their native language. (They are also called by their Spanish name, the Tarahumara.) The race drew some of the top ultrarunners in the world, including Colorado's Scott Jurek, who came in second to a Raramuri athlete. 

True, who was often called Caballo Blanco, died in 2012. The annual race has survived, though it's canceled this year. 

Micah True, a.k.a. Caballo Blanco.

(Luis Escobar)

True became famous in 2009, with the release of the bestselling book "Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen," by Christopher McDougall, in which True was the central character.

Now a documentary continues the story through True's death. "Run Free" screens tonight, Saturday and Sunday at the Denver Film Festival. Filmmaker Sterling Noren and McDougall talked with Colorado Matters host Ryan Warner.