WASHINGTON—After Amir Hekmati was released from Iranian custody in a 2016 deal trumpeted as a diplomatic breakthrough, he was declared eligible for $20 million from a special U.S. government fund as compensation for years of imprisonment that included brutal torture. But payday never arrived, leaving Hekmati to wonder why. The answer has finally arrived: Newly filed court documents reviewed by The Associated Press reveal decade-old FBI suspicions that he traveled to Iran with the goal of selling classified secrets to the government. Hekmati vigorously disputes the allegations, has never faced criminal charges and is challenging a special master’s conclusion that he lied about his visit to Iran and is therefore not entitled to the money. The FBI suspicions help explain the government’s ongoing refusal to pay Hekmati for his ordeal and muddy the narrative around a U.S. citizen, Marine and Iraq war veteran whose release was championed at the U.S. …