Ernest Hemingway may have been driven to kill himself because of his surveillance by the FBI, his close friend and collaborator has said.
Hotchner wrote in The New York Times that he had "regretfully misjudged" his friend's fears of federal investigators, which were dismissed as paranoid delusions for years after his death.
In 1983 the FBI released a 127-page file it had kept on Hemingway since the 1940s, confirming he was watched by agents working for J. Edgar Hoover, who took a personal interest in his case.
Hotchner described being met off a train by Hemingway in Ketchum, Idaho, in November 1960, for a pheasant shoot with their friend Duke MacMullen.
Hemingway, struggling to complete his last work, complained "the feds" had "tailed us all the way" and that agents were poring over his accounts in a local bank that they passed on their journey.
"It's the worst hell," Hemingway said. "The goddamnedest hell. They've bugged everything. That's why we're using Duke's car. Mine's bugged. Everything's bugged. Can't use the phone. Mail intercepted."
Later that month he was committed for psychiatric care at the Mayo Clinic in Minnesota, where he received electric shock treatment. He attempted suicide several times before being released.
A few days after returning home to Ketchum, he shot himself in the head with his favourite shotgun aged 61.
"In the years since, I have tried to reconcile Ernest's fear of the FBI, which I regretfully misjudged, with the reality of the FBI file," wrote Hotchner, the author of 'Papa Hemingway'.
"I now believe he truly sensed the surveillance, and that it substantially contributed to his anguish and his suicide," he said.