In a Tuesday speech on the Senate floor, Nelson said he has spoken in recent days to Mohammad Khazaei, the Iranian ambassador to the United Nations, and pleaded on humanitarian grounds for details on Levinson, who disappeared in Iran in 2007, Associated Press reported.

An AP investigation published last week found that Levinson was working for the CIA – investigating the Iranian government. The US long has publicly described Levinson as a private citizen who traveled to an Iranian island on private business.

Nelson, a member of the Senate Armed Services Committee, said he has offered to the ambassador “if it would in any way help that I am willing to go to Iran, if in any way that it would secure his release. If the Iranian authorities took him, somebody in the government of Iran knows of his whereabouts.”

Nelson underscored that the recent nuclear deal between Tehran and Western nations are at a critical stage with the possibility of a breakthrough in a few months. The Florida Democrat said that Iran can show its goodwill by producing Levinson.

The US has not had “proof of life” in years – Levinson’s family last received photos and video of him in late 2010 and early 2011 – and is not sure who is holding him.

US officials have raised the Levinson case with Iran repeatedly over the years. But until the AP investigation was published, it was not widely known that Levinson was hoping to gather information in his role as an independent contract investigator who expected to be compensated by a group of analysts at the CIA.

Iran’s Foreign Minister Mohammad Javad Zarif, when asked whether he had information about Robert Levinson, said, “I have no idea. What we know is that he is not incarcerated in Iran. We have no traces of him in Iran.”

After he vanished, the CIA at first told lawmakers he had previously done contract work for the agency, but he had no current relationship with the agency and there was no connection to Iran. However, in October 2007, Levinson’s lawyer discovered emails in which Levinson told a CIA friend that he was working to develop a source with access to the Iranian government. The emails were turned over to the Senate Intelligence Committee, which touched off an internal CIA investigation.

NTJ/BA