The family of a part-time consultant for the C.I.A. who vanished a decade ago in Iran filed a lawsuit on Tuesday against that country, claiming that it had used a campaign of deception and lies to conceal its role in his imprisonment.
The lawsuit was filed in a federal court in Washington on behalf of the wife of the missing man, Robert A. Levinson, and their seven children. The action is seeking unspecified damages from Iran for its alleged role in, among other things, inflicting emotional distress on the family of Mr. Levinson, a private investigator who was a former F.B.I. agent.
Other Americans once held by Iran as prisoners have filed lawsuits against the Tehran government, accusing it of hostage-taking, terrorism and torture. But the action involving Mr. Levinson is unusual because Iranian officials have insisted since he disappeared that they know nothing about his whereabouts or what happened to him.
A lawyer who represents Mr. Levinson’s family called such claims hollow, adding that Iran had long been engaged in a campaign of disinformation about the missing man.
“We want justice, and this case calls out for justice,” the lawyer, David L. McGee, said in an interview. “We also want the world to know about Iran’s cruel and cynical behavior.”
A spokesman for Iran’s ambassador to the United Nations did not respond to two emails seeking comment.
The lawsuit could lead to a confrontation between President Trump and Iran over Mr. Levinson’s fate. American law enforcement officials have long believed that elements of Iran’s political, religious or intelligence hierarchy were involved in his capture and detention. But President Barack Obama never challenged Iran with those findings while in office, and Mr. Trump, who vowed in 2015 to bring Mr. Levinson home, has yet to do so.
Mr. Levinson traveled in March 2007 to an Iranian island on a rogue mission to recruit an intelligence source for the C.I.A. He has been seen since then only in a hostage videotape made in 2010 and in a series of photographs. While some experts believe Mr. Levinson died in captivity, his family believes he is still alive. If so, he would now be 69.
The 14-page lawsuit filing does not contain any new disclosures about Mr. Levinson. But the lawsuit asserts that the F.B.I. has “concluded” that the hostage videotape and photographs — neither of which provided clues about his captors’ identity — were part of an “Iranian attempt to create a false scenario that Robert Levinson was being held by some other country.”
Lindsay Ram, an F.B.I. spokeswoman, did not respond directly when asked if the bureau had concluded that individuals or entities in Iran were responsible for Mr. Levinson’s detention.
Last year, Mr. Levinson’s wife, Christine, filed a request under the Freedom of Information Act seeking numerous F.B.I. documents related to the bureau’s long-running investigation into her husband’s disappearance. But the F.B.I. denied her request, stating that since the inquiry personally involved Mr. Levinson, she would have to take steps like getting his approval or providing evidence that he is dead, a copy of that F.B.I. letter shows.
This month, a Florida state judge appointed Mrs. Levinson as her husband’s legal conservator, a posture that could overcome some of the F.B.I.’s objections. But Ms. Ram, the spokeswoman, said that as a matter of policy the bureau does not release documents about cases that are “ongoing.”
Mr. McGee said he was disappointed by the F.B.I.’s position, particularly given the missing investigator’s two decades of service as an agent.
“As long as they keep this investigation open, the F.B.I. is not obliged to tell the family what it has done on Bob’s behalf,” he said.