The book, not yet titled, is scheduled for publication in 2006.
"It's a natural story for John to tell," Stephen Rubin, president and publisher of Doubleday Broadway, said in a statement Wednesday. "It has many of the same themes present in his novels — legal suspense, the death penalty, wrongful conviction, even baseball. It's the ultimate true legal thriller."
According to Doubleday, Grisham thought of the book after reading the obituary of Ronald Keith Williamson, a promising athlete drafted in the early 1970s by the Oakland Athletics. In 1986, he was arrested for the rape and murder of a 21-year-old Oklahoma woman. Williamson was convicted. He was within days of his scheduled execution, in 1999, when DNA testing proved he was innocent.
Williamson died of cirrhosis of the liver in 2004. He was 51.
"Not in my most creative hour could I imagine a story as compelling as Ron Williamson's," Grisham said in a statement.
Grisham won't be the first author of courtroom novels to try nonfiction. Scott Turow, whose best sellers include "Presumed Innocent" and "The Burden of Proof," wrote the nonfiction "Ultimate Punishment," an analysis of the death penalty that was published in 2003.