Iran executed a nuclear scientist who defected to the U.S. in 2009 and later returned to the Islamic Republic under mysterious circumstances a year later, authorities said Sunday, acknowledging for the first time that they had secretly detained, tried and convicted a man authorities once heralded as a hero.

Shahram Amiri vanished in 2009 while on a religious pilgrimage to Muslim holy sites in Saudi Arabia, only to reappear a year later in a series of online videos filmed in the U.S. He then walked into the Iranian interests section at the Pakistani Embassy in Washington and demanded to be sent home.

In interviews, Amiri described being kidnapped and held against his will by Saudi and American spies, while U.S. officials said he was to receive millions of dollars for his help in understanding Iran’s contested nuclear program. He was hanged the same week as Tehran executed a group of militants, a year after his country agreed to a landmark accord to limit uranium enrichment in exchange for the lifting of economic sanctions.

Speaking to journalists Sunday, Iranian judiciary spokesman Gholamhosein Mohseni Ejehi said Amiri was convicted of spying charges as he “provided the enemy with vital information of the country.”

Amiri had access to classified information “and he was linked to our hostile and number one enemy, or the Great Satan,” Ejehi said, referring to the U.S.

Ejehi did not explain why authorities never announced Amiri’s conviction or his subsequent, failed appeals court bid. He said Amiri had access to lawyers.

“He neither repented nor compensated and he was trying to leak some information from inside prison, too,” Ejehi said, without elaborating.

News about Amiri, born in 1977, has been scant since his return to Iran. Last year, his father Asgar Amiri told the BBC’s Farsi-language service that his son had been held at a secret site since coming home.

On Tuesday, Iran announced it had executed a number of criminals, describing them mainly as militants from the country’s Kurdish minority. Then, an obituary notice circulated in Amiri’s hometown of Kermanshah, a city some 500 kilometers (310 miles) southwest of Tehran, according to the Iranian pro-reform daily newspaper Shargh. It announced a memorial service on Thursday for Amiri, calling him a “bright moon” and “invaluable gem.”

Manoto, a private satellite television channel based in London believed to be run by those who back Iran’s ousted shah, first reported Saturday that Amiri had been executed. BBC Farsi also quoted Amiri’s mother saying her son’s neck bore ligature marks suggesting he had been hanged by the state.

The Associated Press could not immediately reach Amiri’s family.

U.S. officials told the AP in 2010 that Amiri was paid $5 million to offer the CIA information about Iran’s nuclear program, though he left the country without the money. They said Amiri, who ran a radiation detection program in Iran, travelled to the U.S. and stayed there for months under his own free will. Analysts abroad suggested Iranian authorities may have threatened Amiri’s family back in Iran, forcing him to return.

But when he returned to Iran and was welcomed by government officials, Amiri said Saudi and American officials had kidnapped him while he visited the Saudi holy city of Medina. He also said Israeli agents were present at his interrogations and that that CIA officers offered him $50 million to remain in America.

“I was under the harshest mental and physical torture,” he said.

Amiri’s case indirectly found its way back into the spotlight in the U.S. last year with the release of emails sent by U.S. Democratic presidential candidate Hillary Clinton while she served as secretary of state. The release of those emails came amid criticism of Clinton’s use of a private account and server that has persisted into her campaign against Republican candidate Donald Trump.

An email forwarded to Clinton by senior adviser Jake Sullivan on July 5, 2010 — just nine days before Amiri returned to Tehran — appears to reference the scientist.

“We have a diplomatic, ‘psychological’ issue, not a legal one. Our friend has to be given a way out,” the email by Richard Morningstar, a former State Department special envoy for Eurasian energy, read. “We should recognize his concerns and frame it in terms of a misunderstanding with no malevolent intent and that we will make sure there is no recurrence.

“Our person won’t be able to do anything anyway. If he has to leave so be it.”

Another email, sent by Sullivan on July 12, 2010, appears to obliquely refer to the scientist just hours before his story became widely known.

“The gentleman … has apparently gone to his country’s interests section because he is unhappy with how much time it has taken to facilitate his departure,” Sullivan wrote. “This could lead to problematic news stories in the next 24 hours.”

(AP)