The fate of three U.S. citizens who have disappeared or been imprisoned in Iran was discussed during Friday's historic conversation between the two nations' presidents, a senior U.S. administration official said.
U.S. President Barack Obama, during his phone call with Iranian President Hassan Rouhani, "noted our concern about three American citizens who have been held within Iran -- Robert Levinson, Saeed Abedini, and Amir Hekmati -- and noted our interest in seeing those Americans reunited with their families," the official said.
Two of the Americans have been tried and convicted in Iranian courts, and the whereabouts of another have been unknown for more than six years.
Here are the most recent developments in the stories of the detained U.S. citizens:
The family of Levinson, a retired FBI agent, has been anxiously waiting for news, any news, about his fate since he vanished during a business trip to Iran in March 2007.
When Rouhani, Iran's new president, arrived in New York, Levinson's wife and children were watching closely for a sign that efforts to find Levinson might move forward.
During an exclusive interview with CNN's Christiane Amanpour, Rouhani offered little when asked what he can tell Levinson's family.
"We don't know where he is, who he is," Rouhani said. "He is an American who has disappeared. We have no news of him."
Yet, like former President Mahmoud Ahmadinejad, Rouhani spoke of cooperation.
"We are willing to help, and all the intelligence services in the region can come together to gather information about him to find his whereabouts," Rouhani told Amanpour. "And we're willing to cooperate on that."
The State Department has said Levinson is believed to be held in southwest Asia.
"We have every reason to believe that he's alive and that the Iranians control his fate," a source with knowledge of the investigation told CNN, a departure from last year when the same source described Levinson as "alive and well."
Questions about his health also remain unanswered. Levinson suffers from diabetes.
Levinson's family said Rouhani's comments, while not directly acknowledging information about Levinson, "are consistent with the commitments made in the past, and [they hope] those promises turn into results."
Spokeswoman Jen Psaki said the State Department said Rouhani's comments about cooperation were welcome.
"We look forward to hearing more specifics on how Iran can help in reuniting Mr. Levinson with his family in the United States as soon as possible."
Both the State Department and Levinson's family deny he was working for the government when he disappeared. The family says Levinson was there on private business investigating cigarette smuggling.
In January, the family released so-called "proof of life photos" they received a few years ago. The photos show him with long, unkempt hair and wearing an orange shirt. He is holding signs written in poor English, including one that reads. " Why you can not help me?"
An FBI task force meets regularly to assess Levinson's case.