Former U.S. marine Amir Hekmati, who is currently being held in Iran on espionage allegations, penned a letter to U.S. Secretary of State John Kerry from behind bars this month.
The letter, obtained by The Guardian after it was smuggled out of a Tehran jail, states that Hekmati's 2011 confession was forced.
"For over two years I have been held on false charges based solely on confessions obtained by force, threats, miserable prison conditions and prolonged periods of solitary confinement," Hekmati wrote.
Click over to The Guardian to read the full transcript of the letter.
A family spokesman confirmed to The Associated Press that Hekmati's sister authenticated the letter, verifying that the handwriting and tone were her brother's.
According to his family, who reside in Michigan, Hekmati was detained by Iranian authorities while visiting his grandmother and was accused of spying for the CIA. In a highly publicized confession that was broadcast on Iranian TV in December, the Iranian-American confessed to the allegations.
Both the U.S. and his family denied the accusations, but an Iranian court convicted Hekmati on espionage charges and sentenced him to death. Iran's Supreme Court nullified the sentence in March 2012 and awarded Hekmati a retrial. However, he has yet to return to court and has remained in prison.
Aside from claiming that his confession was extracted under duress, Hekmati also accused Iranian authorities of using "unlawful tactics" to keep him imprisoned and divulged the "miserable prison conditions" he's been forced to endure.
"This is part of a propaganda and hostage-taking effort by Iranian intelligence to secure the release of Iranians abroad being held on security-related charges," his letter states, per The Guardian.
Last month, on the day before the two-year anniversary of the date Hekmati was imprisoned, Kerry called on the Iranian government to release the U.S. citizen. In a statement, the secretary said that Hekmati belongs at home with those who love and miss him.