“I have been treated well and I need the help of the United States government,” he said on the tape|For more on this case and for CBS News senior correspondent John Miller, a former FBI assistant director’s analysis, watch the video above|The picture on the billboard was taken from a mysterious video that the family received nearly two years ago|”I immediately knew it was Bob, and so I watched carefully, trying to figure out what the message was,” says Christine}

(CBS News) There may be a break this morning in the search for retired FBI agent Robert Levinson. He vanished five-and-a-half years ago while working in Iran.

Since then, his family and the FBI have pleaded with the Iranian government for information. Now, CBS News’ interview with Iranian President Mahmoud Ahmadinejad may shed some light on the case.

As world leaders gather in New York for the United Nations General Assembly, their motorcades are bound to pass one of the many billboards asking for their help in locating Levinson. But the intended audience for the ad campaign may be just one man: Ahmadinejad.

(In an interview to air Wednesday on “CTM,” Ahmadinejad spoke to Charlie Rose and Norah O’Donnell about the threat of an attack on Iran’s nuclear facilities, and how his country would respond. Watch a preview from that interview below.)

CBS News has learned that the Iranian leader may have the answers to the mystery that has consumed Levinson’s family.

As CBS News walked through Times Square with Christine Levinson and her son Daniel, neither of them were prepared to see the face of Robert Levinson staring back from an electronic billboard. The picture on the billboard was taken from a mysterious video that the family received nearly two years ago. Levinson, pale and gaunt, being held somewhere, and 화성출장업소 pleading for help.