Story highlights Missing former FBI agent's family files suit against the government of Iran

Robert Levinson went missing 10 years ago; officials believe he was abducted by Iran

(CNN) The family of a former FBI agent who disappeared in Iran a decade ago is suing the country, according to court documents obtained by CNN.

The wife and children of Robert Levinson, a former FBI agent whom US investigators believe is being held in Iran, filed a suit with the US District Court in Washington, D.C.

The complaint states that the family is filing suit under the Foreign Sovereign Immunities Act "for injuries suffered by each of them as a result of Iran's unlawful acts of hostage taking, torture and other torts."

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If indeed Iran does have him in custody, Levinson would be the longest held US civilian by a foreign government. Iran has denied having anything to do with his disappearance and has said they don't know where he is.

CNN is attempting to reach the Iranian government for response to the lawsuit but most offices are closed for New Year celebrations.