Ali Hekmati's doctors said his brain cancer is incurable and the Iranian-American's dying wish is to see his son "to hug and kiss him," CNN reported.
Amir Mirzaei Hekmati, a former U.S. Marine and decorated Iraq war veteran, was arrested on espionage charges in August 2011 just weeks after arriving in Iran to visit his grandmother.
Hekmati, who was born in Arizona, holds both U.S. and Iranian citizenship.
The State Department has called his case a gross miscarriage of justice and denied that Hekmati was spying for the United States.
Iranian President Mahmoud Ahmadinejad, in New York to address the United Nations General Assembly, has so far declined to meet with the Hekmatis or discuss their son's case.
"I'm sure that he's going to hear my voice," said Hekmati's mother Behnaz. "He's in the United States; he's going to listen to me."
Notable deaths of 2014 [PHOTOS]