WASHINGTON: The co-author of “Three Cups of Tea,” the best-selling but disputed tale of an American mountaineer who built schools in Afghanistan and Pakistan, committed suicide, officials said Monday.

David Oliver Relin, 49, died November 15 as a result of “blunt force head injuries,” Tom Chappelle, a deputy medical examiner in Multnomah County, Oregon, told AFP by telephone.

Chappelle declined to give details, but confirmed that suicide was the stated cause of death on the death certificate just issued by his office.

Relin, a journalist who specialized in humanitarian issues, co-wrote “Three Cups of Tea” with Greg Mortenson, whose chance encounter with Pakistani villagers after a bid to climb K2 in 1993 led to him building dozens of schools, mostly for girls, in poor rural parts of Pakistan and Afghanistan.

It sold more than four million copies -- and became required reading at the Pentagon as a guide for wooing hearts and minds away from the Taliban -- until allegations surfaced in 2011 that Mortenson fabricated much of his story.

The CBS News program “60 Minutes” said many of the schools supposedly run by Mortenson's charity had never opened, while others were deserted or operating without links to Mortenson.

Mortenson stood by the book, but in April this year he repaid $1 million to his charity, the Central Asia Institute, and resigned from its board after an investigation turned up evidence of “financial transgressions.”