Father fears he may never see his son imprisoned in Iran Mother appeals publicly to President Ahmadinejad for Amir Hekmati's release Former U.S. marine is unaware his father is dying of brain cancer "That's my last wish, to hug him and kiss him," his father says "They forced him" to confess to espionage, his mother says. That's not true Flint, Michigan (CNN) -- With Iran's president in New York for the UN General Assembly, an Iranian-American family in Michigan is appealing to Mahmoud Ahmadinejad publicly to have their son - imprisoned in Iran on espionage charges - released before his father dies of brain cancer. In a hospital interview with CNN, the father of former US marine Amir Mirzaei Hekmati, says if his son is not released soon, he will pass away without ever seeing him again. "Please, please, please release an innocent man," pleaded the father, Ali Hekmati, who had a cancerous tumor removed from his brain. Reunite him with his father, his mother. Ali Hekmati's doctor says the cancer is incurable and that he has just months to live. He will undergo radiation treatment and chemotherapy in hopes of extending his life long enough embrace his son one last time. "That's my biggest fear, that he may not see me and that's my last wish, to hug him and kiss him before I pass to the other side," Ali Hekmati said. Amir Hekmati, a former marine and decorated Iraq war veteran, was born in Arizona and raised in Nebraska and Michigan. Within weeks of setting foot in Iran for the first time in August 2011 to visit his grandmother, he was arrested, interrogated, imprisoned. Months later he appeared on Iranian TV, showcased as a confessed CIA operative. They forced him to do that. That's not true," said Hekmati's mother, Behnaz, referring to the alleged confession. "They knew he was a military (soldier) because he told the Embassy of Iran he was in the military," she adds, explaining that her son checked with Iranian authorities in the United States before making the trip. The U.S. State Department also denies Hekmati was spying for the U.S. government and calls the case a gross miscarriage of justice. We never thought he should have been arrested. We've been trying, because he's a dual U.S.-Iranian national, we've been trying to get access to him since he was originally locked up," said State Department spokesperson Victoria Nuland. The Iranians have never allowed us to go to see him. A court convicted Hekmati of espionage, sentencing him to death, but he has since been granted a retrial. He remains in prison in Iran and has no idea that his father is dying, his family said. He has a government-approved lawyer in Iran, but contact with him has been sporadic. His father's neurosurgeon, Dr. Ryan Barrett, believes the emotional stress of his son's imprisonment will make cancer treatment more challenging. Although the Iranian president has thus far declined to meet with the Hekmatis or discuss Amir's case, the former marine's mother is convinced Ahmadinejad will hear their pleas. I'm sure that he's going to hear my voice. He's in the United States; he's going to listen to me," said Amir's mother. I just want him to hear my voice as a mother. She has traveled to Iran three times and been granted limited visits. She described her son as disheartened and completely confused as to why he was arrested. He is skinny, pale, like a chalk, his face was like chalk. Hair was shaved, had a beard, he walked like this and the feet was together he walked like a robot," she said. He couldn't stop crying and he was (saying) 'I don't know why I'm here,' Mom. CNN's Azadeh Ansari contributed to this report.