Grann graduated from Connecticut College in 1989 with a B.A. in Government. He received a Thomas J. Watson Fellowship and conducted research in Mexico, where he began his career as a freelance journalist. He received a masters degree in international relations from The Fletcher School of Law and Diplomacy in 1993.

He was hired as a copy editor at The Hill (a Washington, D.C.-based newspaper covering the United States Congress) in 1994. The same year, he earned a masters degree in creative writing from Boston University. He was named The Hill's executive editor in 1995. He became a senior editor at The New Republic in 1996. He joined The New Yorker in 2003 as staff writer. He was a finalist for the Michael Kelly Award in 2005, and was awarded the 2009 George Polk Award and 2009 Sigma Delta Chi Award for his New Yorker piece "Trial By Fire," which has been described as the first thoroughly documented case of the execution of an innocent man under the modern American judicial system.

Grann married television producer Kyra Darnton in 2000. The couple has two children, and as of 2009 resided in New York City.

Other publications

Grann's stories have appeared in several anthologies, including What We Saw: The Events of September 11, 2001, The Best American Crime Writing of 2004 and 2005, and The Best American Sports Writing of 2003 and 2006. He has also written for The New York Times Magazine, The Atlantic, The Washington Post, The Wall Street Journal, and The Weekly Standard.

A Tale of Deadly Obsession in the Amazon tells the story of the legendary British explorer Percy Fawcett who, in 1925, disappeared with his son in the Amazon while looking for the Lost City of Z. For decades, explorers and scientists have tried to find evidence of his party and the Lost City of Z. More than 100 people perished or disappeared seeking Fawcett. Grann made his own journey into the Amazon, revealing new evidence about how Fawcett died and showing that Z may have indeed existed.Heckenberger, Michael. The Ecology of Power: Culture, Place, and Personhood in the Southern Amazon, A.D. 1000—2000. New York: Routledge, 2005. ISBN 0415945984; Heckenberger, Michael J.; Kuikuro, Afukaka; Kuikuro, Urissapá Tabata; Russell, J. Christian; Schmidt, Morgan; Fausto, Carlos; and Franchetto, Bruna. "Amazonia 1492: Pristine Forest or Cultural Parkland?" Science. April 25, 2003;Heckenberger, Michael J. "Manioc Agriculture and Sedentism in Amazonia: The Upper Xingu Example." Antiquity. September 1998. The book was optioned by Brad Pitt's Plan B production company and Paramount Pictures.

An anthology of 12 previously published Grann essays Tales of Murder, Madness, and Obsession was published in March, 2010.