One of the speakers at last year's Telluride Mountainfilm Festival in western Colorado was convicted this March of federal felonies. But Tim DeChristopher will be back again this year to talk about his disruption of federal gas leasing at an auction in Utah.

Not so Greg Mortenson, the embattled former mountain climber who has been accused of taking giant liberties with the truth in his inspiring book, "Three Cups of Tea," as well as with using donations intended to build schools for girls in Afghanistan and Pakistan as his "own private ATM."

Festival organizers say that they have accepted Mortenson's offer to step down from his scheduled roles this year as a film judge and panel speaker. However, the door might still be open to the writer -- who spoke at last year's festival over the Memorial Day weekend  -- if he will agree to be publicly grilled at Mountainfilm about the charges leveled against him.

Mortenson says he first showed up at Mountainfilm in 1981, when he was a young climber and the festival was only three years old. The event has broadened over the decades, becoming more a festival of ideas, with mountains only occasionally the focus. Its motto is "Celebrating indomitable human spirit."

Mortenson's story seemed a perfect fit for that motto. Following a failed attempt to summit K2, a mountain on the Pakistani border, he said that he was kidnapped by the Taliban. Afterward, he vowed to build schools in Afghanistan, especially for girls. His efforts have won almost universal praise; President Obama even donated $100,000 of his Nobel Peace Prize award to Mortenson's Montana-based organization, the Central Asia Institute. Altogether, the organization has raised $60 million in a few short years based on Mortenson's compelling story and his many riveting talks at Telluride and other places.

But the recent "60 Minutes" segment about Mortenson's embellishments raises questions that even his staunchest defenders admit are serious. Jon Krakauer, author of "Into Thin Air" and more recently "Where Men Win Glory: The Odyssey of Pat Tillman," told "60 Minutes" that Mortenson's story is a "beautiful story, and it's a lie."

Titling his just-published 75-page article about Mortenson, "Three Cups of Deceit," Krakauer said it now appears that Mortenson was never kidnapped by the Taliban. He also said that the Montana nonprofit founded by Mortenson claimed expenses for promoting his books, but never received any of the profits from book sales; Mortenson kept the royalties for himself. "Three Cups of Tea" has now sold 4 million copies. Perhaps even more damaging are Krakauer's allegations that Mortenson used the nonprofit organization to fund a lavish lifestyle that included the use of personal jets.

The American Institute of Philanthropy has also been sharply critical of Mortenson's organization. In 2009, it said the organization spent $4.6 million on "outreach," as compared to less than $4 million for construction, administration and other expenses directly related to schools. In the last week, Mortenson's admirers have defended him, but some more cautiously than others.

In his New York Times column, Nicholas Kristof wrote that he was inclined "to reserve judgment until we know more, for disorganization may explain more faults than dishonesty." And, he added, he was "willing to give some benefit of the doubt to a man who has risked his life on behalf of some of the world's most voiceless people."

Peter Kenworthy, executive director of Mountainfilm, said the first instinct of the festival organizers was to reach out to Mortenson, to let him know they were thinking of him. But now, after more fully assessing the evidence, Kenworthy said he's less inclined to think any good can come from Mortenson's presence. "I am afraid that if Greg were to come, it would be only a lose-lose situation," he said.

Kenworthy, who directs a $1.5 million nonprofit, said that all such organizations have a clear need for proper policies, procedures and process, and that it appears that Mortenson did things as a nonprofit director that were clearly verboten. The case of Tim DeChristopher is different, he said. "As long as we support what they're doing, that's fine. In Greg's case, it's not the kind of controversy we're looking for."

Allen Best is a contributor to Writers on the Range, a service of High Country News (hcn.org). He lives in the Denver area where he is the editor of Mountaintownnews.net and has attended the Mountain Film Festival 20 times.