The family of a retired FBI agent who went missing in Iran in 2007 released a proof-of-life video Friday showing him held hostage by unknown kidnappers and issuing a simple plea to US officials: "please help me get home."
American Robert Levinson appeared weary and thin but unharmed in the footage, the first substantial evidence that he is alive and being held against his will.
The year-old video was posted online accompanied by footage of his wife and son pleading to his captors to free the 63-year-old father of seven.
"I have been treated well, but I need the help of the United States government to answer the requests of the group that has held me for three and a half years," Levinson said in the 54-second clip in which he is shown seated in front of what appears to be a grey concrete wall.
"I am not in very good health. I am running very quickly out of diabetes medicine," he said, his voice quavering. "Please help me get home. Thirty-three years of service to the United States deserves something."
A former US State Department official familiar with the case said the video was accompanied by a demand for the release of several US-held prisoners.
The video did not reveal where Levinson is being held, or by whom. His wife said Friday that she received the footage "a little more than a year ago."
"Since we received that video, we tried to get in touch with the group that is holding Bob," Christine Levinson told CNN.
"Unfortunately, we have not received any response from them and we feel that this is a way to try and reach them with our plea."
Mystery shrouds the fate of Levinson, who disappeared on Iran's Gulf island of Kish in March 2007.
His wife said Levinson, who retired from the Federal Bureau of Investigation more than a decade ago, had traveled to Kish as a private investigator to look into cigarette counterfeiting and was last heard from on March 8, 2007.
FBI officials have been poring over the video for clues, including Levinson's remarks that a "group" was holding him hostage, suggesting it may be a terror network or crime cartel rather than a government.
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He said he had been held "here" during his captivity, suggesting he had not been moved to different locations.
Iran has denied holding Levinson. Earlier this year Secretary of State Hillary Clinton said Washington had received information that he was in southwest Asia, and she called on Tehran to help locate him.
At the time of the UN General Assembly in September, Iranian President Mahmoud Ahmadinejad expressed a willingness to help in the case, but "I have not had any contact with them recently," Levinson's wife said.
US officials expressed optimism this year that Levinson was alive, but the family's decision to publicly release the video and make a direct appeal to Levinson's captors suggests that a diplomatic push has yielded little.
State Department spokeswoman Victoria Nuland said the United States has been in touch with Iran through the Swiss embassy in Tehran -- which represents US interests in the absence of diplomatic relations -- and that "efforts will continue in all directions."
"Obviously we're all hopeful that this will bring more leads," she told reporters, while declining to say if Levinson is believed to be in Iran.
While it remained unclear where he's being held -- the border regions of Pakistan and Afghanistan are possibilities -- "it's going to take the Iranian government to say 'Let him go' in order for him to be released," Reza Marashi, research director for the Washington-based National Iranian American Council, told AFP.
The video was released at a time of high political tension over Iran's nuclear program. The United States accuses Iran of masterminding a plot to kill the Saudi envoy to Washington, and more recently the Islamic republic claimed it brought down a US spy drone.
"Bob Levinson has very sadly become a bargaining chip in this institutionalized enmity between the United States and Iran," Marashi said.
The Levinson family website showed his wife and son making a desperate attempt to contact the kidnappers and have "the pillar of our family" freed.
"We don't know what else to do. Please tell us what you want, and please help us bring my father home," said son David.
"We are not part of any government, and we are not experts on the region. No one can help us but you," he said somberly.
Levinson's wife "will continue to do everything I can to bring you home alive," she said. "We love you. We miss you every day. We will not abandon you."