All american troops will leave next year if karzai refuses to ryan. The wish of one american family granted. Former fbi agent robert levinson has been held hostage longer than any other american and... See More
All american troops will leave next year if karzai refuses to ryan. The wish of one american family granted. Former fbi agent robert levinson has been held hostage longer than any other american and his family is hoping tonight that the recent thaw in u.S. Relations will bring him home soon. Here's abc's brian ross. Please help me get home. Reporter: As of today, no american has been held hostage longer than former fbi agent robert levinson. For him it is day 2,455 since he disappeared in iran. The once clean cut 65-year-old floor man last seen alive in this video releases two years ago in a prison suit with a long beard and wild gray hair. 33 years of service to the united states deserves something. Reporter: There were signs of some progress today with an unusually delicate statement form the white house, "respectfully" asking, not demanding, that iran help secure levinson's safe return. It's a code word in islamic republic circles. It's a country that tends to be particularly sensitive about how it is approached and how you ask questions of it. Reporter: Levinson was reported missing during a trip he took in 2007 to iran's kish island as a private investigator after he had retired from the fbi. Iran has denied holding him, but investigators don't believe that. Levinson's family hopes that seeming thaw in u.S.-Iranian relations could lead to his release, although u.S. Officials said today his case was not part of the recent talks in geneva. But we have raised, repeatedly raised his case and the case of other detained american citizens. Reporter: Iran has admitted to holding at least two other americans. Amir hekmati, a former marine of iranian descent from michigan, visiting his grandmother but accused of being a spy. And saeed abedini, an iranian-american pastor form idaho, sentenced to eight years in prison for establishing churches in iran. Levinson's wife chris said this seventh thanksgiving without bobby will be almost impossible to bear, as it will be for the other two families as well. So hard. Okay, brian. Thanks very much.
This transcript has been automatically generated and may not be 100% accurate.