WASHINGTON - An American who vanished nearly seven years ago in Iran was working for the CIA on an unapproved intelligence-gathering mission that, when it came to light inside the government, produced one of the most serious scandals in the recent history of the CIA - but all in secret, an Associated Press investigation found.

The CIA paid Robert Levinson's family $2.5 million to head off a revealing lawsuit. Three veteran analysts were forced out of the agency, and seven others were disciplined.

The United States publicly has described Levinson as a private citizen.

That was just a cover story. In an extraordinary breach of the most basic CIA rules, a team of analysts - with no authority to run spy operations - paid Levinson to gather intelligence from some of the world's darkest corners. He vanished while investigating the Iranian regime for the U.S. government.

Details of the disappearance were described in documents obtained or reviewed by the AP, plus interviews over several years with dozens of current and former U.S. and foreign officials close to the search for Levinson. Nearly all spoke on condition of anonymity because they were not authorized to discuss the case.

There is no confirmation who captured Levinson or who may be holding him now. Although U.S. authorities have investigated possible involvement of drug traffickers or terrorists, most officials say they believe Iran either holds him or knows who does.

The AP first confirmed Levinson's CIA ties in 2010 and continued reporting to uncover more details. It agreed three times to delay publishing the story because the U.S. government said it was pursuing promising leads to get him home.

The AP is reporting the story now because, nearly seven years after his disappearance, those efforts have repeatedly come up empty. The government has not received any sign of life in nearly three years. Top U.S. officials, meanwhile, say his captors almost certainly already know about his CIA association.

There has been no hint of Levinson's whereabouts since his family received proof-of-life photos and a video in late 2010 and early 2011. Iran denies any knowledge of Levinson's whereabouts and says it's doing all it can.