Relin, who co-wrote the 2006 book with Greg Mortenson about how Mortenson, a former mountain climber, started building schools in Pakistan and Afghanistan, "suffered emotionally and financially as basic facts in the book were called into question," the Times says.
His family said Relin "suffered from depression" but would not give further details surrounding his death.
As a journalist during the '90s, Relin focused on telling humanitarian stories including articles about child soldiers and traveling to Vietnam. This work was what led Viking Books to pair him with Mortenson.
Three Cups of Tea sold over four million copies, but in 2011 60 Minutes and author Jon Krakauer – who released an E-book titled Three Cups of Deceit – both questioned the validity of major points in the book.
Relin did not speak publicly about the accusations, but hired a lawyer to defend him in a federal lawsuit that claimed he and Mortenson defrauded readers. The suit was dismissed earlier this year.
Relin is survived by his wife, Dawn; his mother, Marjorie; his stepfather Cary Ratcliff; and his sisters Rachel Relin and Jennifer Cherelin.