The U.S. believes that the Iranian government or its proxies are holding a retired FBI agent hostage.

Robert Levinson, a 64-year-old private investigator and FBI veteran, went missing off of the Iranian island of Kish in 2007. U.S. officials previously believed that terrorists had kidnapped him, and publicly welcomed the "assistance" of the Iranian government in getting Levinson home. But the Associated Press' Adam Goldman and Matt Apuzzo report that U.S. intelligence officials have come to believe that Iran is behind Levinson's five-year captivity.

The photo above showing a gaunt, emaciated and heavily bearded Levinson was provided to the AP by Levinson's family. He wears an orange jumpsuit, mimicking the garb of the first wave of Guantanamo detainees, and holds a sign reading "I Am Here in Guantanamo Do You Know Where It Is?" According to the Levinson family's website, the 6'4" Levinson weighed 225 pounds when he went missing on what the website describes as a "business trip" to Kish Island.

Levinson's family received this and other photographs of him in 2011, around the time his wife and son received a proof-of-life video of a scared Levinson. Levinson looked more robust on camera then, suggesting a variance in time between the photos and the video. The former FBI agent says on camera that he was "running out of diabetes medicine" and pled to Washington for aid: "Thirty-three years of service to the United States deserves something."

Supposedly, Levinson was investigating cigarette smuggling in 2007 on the island of Kish, which is a free-trade zone in the Persian Gulf that does not require travel visas for U.S. citizens. The AP describes it as a nexus of illicit activity.

Initially, U.S. intelligence believed that a terrorist group had taken Levinson prisoner – but no ransom or demand has followed word of his capture. Clues suggested that Levinson might have been taken to south Asia. The video was traced to an Internet cafe in Pakistan in 2010, and "Pashtun wedding music" is audible in the video's background, the AP reports.

But a frustrating, years-long effort to find Levinson has led intelligence agents to a different conclusion: the Iranians or their proxies are holding him. That conclusion is inferential, rather than based on hard intelligence: "The tradecraft used to send [the photos and videos] was too good, indicating professional spies were behind them," according to Goldman and Apuzzo.

U.S. officials have said very little about Levinson's case – and what they have said has apparently been misleading, as a gambit to entice the Iranians into releasing Levinson. In March 2011, for the fourth anniversary of Levinson's disappearance, Secretary of State Hillary Rodham Clinton referred only to Levinson being held "somewhere in southwest Asia." Referring to an offer of Iranian "assistance," Clinton added, "We would appreciate the Iranian government's efforts in this matter." U.S. officials talking anonymously to the AP have concluded the Iranian government lied about conducting raids to learn Levinson's whereabouts.

Levinson's relatives spoke out to the AP because, they say, they have heard nothing further from Washington about the captive. "There needs to be a lot more public outcry," Christine Levinson told the AP. In August, the family commemorated Levinson's 2,000th day in captivity, which made him the second-longest-held hostage in U.S. history. They've rented a billboard in Times Square to call attention to his case.

But the U.S. has evidently suspected for years that Iran is behind Levinson's extended imprisonment. It isn't clear what Washington is willing to do – or can do – to free him.