A former FBI agent who vanished in Iran in 2007 has appeared pleading for help in a hostage video, prompting speculation that he has been moved to Pakistan or Afghanistan.
It offered the first visible clues to a case that has confounded Washington since Robert Levinson disappeared during a trip to the resort island of Kish.
He was reportedly investigating a cigarette smuggling ring for a client of his security consultancy.
The last contact with his wife was a call from Dubai.
It was assumed that the Iranian government had captured him.
The footage of Mr Levinson was filmed in November last year, but only released by his family on Friday.
It shows Mr Levinson (63) looking gaunt but apparently unharmed. He asks the US government "to answer the requests of the group that has held me for three-and-a-half years", though he does not identify the group.
His wife Christine and son David posted the video on a website dedicated to his release and issued their own plea to his captors: "Please tell us your demands so we can work together to bring my father home safely."
Photographs of Mr Levinson, which the family received several months after the video, were also published. His hair and beard are much longer and his clothes hang loosely off his thinning frame.
Tehran has repeatedly denied any involvement in the disappearance. But following the release of the video, what was regarded as a diplomatic incident is now regarded as more likely to be a hostage situation.
The video contained clues suggesting Mr Levinson was being held in Pakistan.
The photographs were, however, traced to an internet address in Afghanistan. He wore an orange prison jumpsuit like those worn by detainees at the US military prison at Guantanamo Bay.
Either theory would suggest that the Iranians passed him on to Pashtun groups.
However, there is also a view that the Iranians disguised the internet route through which the material was sent and are still holding him. (© The Daily Telegraph, London)