David Oliver Relin, who co-authored the controversial book Three Cups of Tea with Greg Mortenson, has died. He was 49.

Medical examiner Peter Bellant says Relin committed suicide in the Portland-area town of Corbett on Nov. 14.

A freelance writer who often investigated social issues involving children, Relin had been depressed, according to his family.

He had reportedly had a difficult relationship with Mortenson, whose Three Cups of Tea tells the story of how the former mountain-climber became motivated to build schools for girls in Pakistan and Afghanistan.

In an introduction Relin wrote for Three Cups of Tea, he wrote that Mortenson's "fluid sense of time made pinning down the exact sequence of many events in this book almost impossible."

The bestseller sparked controversy after TV's 60 Minutes and author Jon Krakauer launched an investigation into Mortensen’s story and concluded that the book contained numerous fabrications. Krakauer published an e-book that questioned the truth of a key story in Mortenson’s tale: that of his rescue by villagers following a mountaineering mishap.

Questions also arose about who actually built the schools Mortenson wrote about.

Though he acknowledged some of the events in Three Cups of Tea were compressed over different periods of time, Mortenson denied any wrongdoing. Relin did not comment on the controversy, though he hired a lawyer to defend him in a U.S. federal lawsuit concerning Three Cups of Tea.

That lawsuit was brought by readers who said they had been tricked into contributing to Mortenson's charity Central Asia Institute by a false story. It was dismissed in April by U.S. District Judge Sam Haddon.

In an August 2011 court filing, Relin's attorney Sonia Montalbano said the litigation "had a negative impact on Relin's livelihood as an author."

She said "Relin does not personally maintain any insurance for this litigation, which means that he has to personally fund his defence."

Relin, born in Rochester, N.Y., was educated at Vassar College. In the 1990s, he spent two years in Vietnam writing about how the country was opening up to the world. He was a contributing editor for Parade and Skiing magazines and had won the Kiriyama Prize in 2007 for Three Cups of Tea.

At the time of his death, Relin had completed a new book about two doctors working to cure cataract-related blindness in the developing world. It is scheduled for publication by Random House in spring 2013.

He is survived by his wife, stepfather and two sisters.

With files from The Associated Press