Secretary of State Mike Pompeo announced on Monday – the 40th anniversary of the Iran hostage crisis – that the reward for information leading to the recovery of missing American Robert Levinson has been increased to $20 million. Levinson disappeared in Iran in 2007 at the age of 58.

Fox News noted on Monday that if Levinson is still alive, he would be the longest-held American hostage in history. Levinson is a former FBI and DEA agent working as a private investigator when he disappeared from a hotel on Iran’s Kish Island and has been seen only twice since then: once in a hostage video sent to his family in 2010, and then in some photos sent in 2011. His family maintains a “Help Bob Levinson” website that tracks the time he has been missing down to the second.

Levinson was ostensibly in Iran working on a cigarette smuggling case, but in 2016 a source told Fox News he was working on an unauthorized CIA mission to help recruit an American fugitive named David Belfield (later known as Dawud Salahuddin) wanted in connection with the murder of an Iranian diplomat in Maryland in 1980.

The Iranian government claims it had nothing to do with his disappearance and does not know his whereabouts. Both Levinson’s family and the U.S. government have rejected Iran’s denials.

The FBI has long offered $5 million dollars for information leading to Levinson’s recovery. Secretary of State Pompeo added a $20 million reward from the State Department during his remarks on the 40th anniversary of Iran taking over 50 Americans hostage at the U.S. embassy in Tehran in 1979.

“Forty years later, the revolutionary regime in Tehran has proven, time and again, that its first acts after gaining power were a clear indication of its evil character. The regime continues to unjustly detain Americans and to support terrorist proxy groups like Hezbollah that engage in hostage taking,” said Pompeo.

“The Trump Administration has made clear that the regime in Iran must release all missing and wrongfully detained Americans, including Robert Levinson, Xiyue Wang, Siamak Namazi, and others. We will not rest until they are reunited with their families,” he said.

Pompeo flatly stated Levinson was “taken hostage in Iran with the involvement of the Iranian regime.”

“While the Iranian regime’s decision to jail our diplomats has cast a 40-year shadow over our relations, the United States knows that the longest-suffering victims of the Iranian regime are the Iranian people. We wish nothing more for them than a future with a truly representative government and friendship with the American people,” he concluded.

Xiyue Wang is a Princeton University graduate student who was detained by the Iranian government during a research trip to Tehran, accused of espionage and incarcerated in Iran’s hellish Evin prison on a ten-year sentence. Princeton University strongly denies the charges of espionage and the United Nations considers his detention “arbitrary.”

Siamak Namazi, 47, was arrested along with his 82-year-old Iranian-American father Baquer Namazi, whose health has fared poorly during his imprisonment. The Namazis were on a business trip to Iran when they were arrested and charged with “collaborating with a foreign government.” Siamak is being held in Evin prison, while Baquer was granted a medical release when his health began deteriorating, although he is not allowed to leave Iran.

The Levinson family released a statement on Monday applauding the increased reward for information about his whereabouts, saying it sends a “clear message from our government of how important it is that Bob Levinson be returned to his family and friends who love him.”

“All the Iranian authorities need to do is send him home,” the family said.

“We wish to express our deep appreciation to President Trump and everyone in the Administration who is working hard every day to bring Bob Levinson home. Today’s announcement shows their commitment to that mission. We are grateful, and we look forward to the day when our husband and father will be able to thank them in person,” they added.

Pompeo on Monday also announced U.S. Treasury Department sanctions against “nine appointees and representatives of Ali Khamenei, the Iranian regime’s unelected Supreme Leader, whose office is responsible for advancing Iran’s radical agenda.”

Two of those individuals have been linked to the 1983 bombing of the U.S. Marine barracks in Beirut, which killed 241 U.S. personnel, and the 1994 bombing of the Argentine Israelite Mutual Association.

“The designation seeks to block funds from flowing to a shadow network of Khamenei’s military and foreign affairs advisers who have for decades oppressed the Iranian people, supported terrorism, and advanced destabilizing policies around the world,” Pompeo said.