The family of US hostage Robert Levinson are calling on Iranian authorities to question the mysterious American killer who was the last to see him.
Mr Levinson, the longest held US hostage, disappeared in Iran in 2007 in the resort island of Kish.
The former FBI agent was on a CIA mission to the country at the time.
His family want the authorities to question American fugitive Dawud Salahuddin who is the last person known to have see him.
Salahuddin, an American fugitive living in Iran, is wanted for the assassination of a former Iranian diplomat in Maryland in 1980.
The Tehran-based lawyer representing the Levinson family, Mohammad Hossein Aghasi, has asked for Salahuddin to be interviewed.
He said: “I presented a person named Dawud Salahuddin, whose real name is David Theodore Belfield. He committed murder in the US and took asylum in Iran. He was at the hotel with Mr Levinson when he went missing.
“I met this person at the Sheraton Hotel in Tehran [date undisclosed] and he made some contradictory statements.
“I conveyed this to the security agencies and the prosecutor’s office and told them that if they really want to find the truth, they should summon and question this person.
“Unfortunately, they ignored the matter for eight years and when the assistant prosecutor finally agreed to summon him, they said his address in Gohardasht [in the city of Karaj] had changed and they don’t have any other address for him. But a person who has taken asylum cannot move around in Iran without permission from legal authorities. We have made several inquiries but haven’t received an answer.”
The request comes as Iran acknowledged for the first time it has an open case before its Revolutionary Court over the 2007 disappearance.
In a filing to the United Nations, Iran has said the case over Robert Levinson was “on going,” without elaborating.
The Trump administration has renewed efforts to find him with an offer of $20 million for information the reward is in addition to $5 million earlier offered by the FBI.