BRUSSELS (Reuters) - When Iran and the United States sealed the implementation of a deal to curb Tehran's nuclear program with a prisoner exchange last month, Siamak Namazi was among the detainees some expected to be freed by the Iranian authorities.
The businessman with dual U.S.-Iranian citizenship was on a list of four prisoners to be released published by the official Islamic Republic News Agency and the Tabnak website on the day of the swap, Jan. 16. His name was withdrawn with an apology but no explanation.
U.S. Secretary of State John Kerry told reporters the following day he had commitments from Iran that Namazi's case would be resolved.
But the 44-year-old Dubai-based executive, distinguished by the World Economic Forum as a "Young Global Leader", is still in Tehran's Evin prison, where former political inmates say torture is frequent during interrogations. Close friends say his conditions have deteriorated.
While Iran announces multi-billion-euro deals with European multinationals, Namazi's case sends a chilling message to expatriates who hope to participate in the economic opening following the lifting of sanctions.
Far from being welcomed back for their skills and international connections, they may end up behind bars or worse.
Namazi has not been charged with any offense and Iranian justice authorities declined in response to Reuters requests to give an official explanation for his continued detention.
Asked what it was doing to win his release, the U.S. State Department declined comment on the individual case, citing "privacy concerns".
"The U.S. government does everything and will continue to do everything it can on behalf of its citizens detained around the world who request our assistance," said Sam Werberg, press officer for the Office of Iranian Affairs.
Friends say Namazi may have become a pawn in factional struggles among hardliners, pragmatists and reformers, each with economic as well as political interests. Some fear he may be being softened up for a televised "confession" - a specialty of Iran's judicial system.
Conservatives close to Supreme Leader Ayatollah Ali Khamenei have warned that Iranian-Americans may use business ventures to infiltrate Iran and bring about a soft version of the "regime change" that U.S. hawks have long sought to achieve in Tehran.
"They connect dual citizens like Siamak who are active in business and society as 'agents of infiltration', which is a complete misperception," said Bijan Khajehpour, a Vienna-based business consultant who is Namazi's cousin by marriage.
Some Iranian political experts, unwilling to be identified because of the sensitivity of the case, say Namazi may have been arrested because he is seen as part of business circles close to ex-president Akbar Hashemi Rafsanjani, a veteran power broker.
Rafsanjani and current President Hassan Rouhani are backing pragmatic and reformist candidates in an effort to wrest control of parliament from conservatives in elections on Feb. 26.
Hardline clerics in the Guardian Council loyal to Khamenei have barred hundreds of candidates from contesting the poll, questioning their loyalty to the Islamic Republic system.
Five Iranian-American groups wrote to Kerry last week urging him to work for the release of Namazi, who they said had been "left behind". They called him "an American who has worked tirelessly as a bridge-buider of cultures, countries, and faiths".
A fellow Young Global Leader from the United States, who requested anonymity, said she had been impressed by Namazi's passion for opening up his country to the world.
"It sends a chilling message to other Young Global Leaders. People fear engaging economically with Iran when someone who advocates for investment is thrown in jail," she said.
Before moving to Dubai, Namazi worked until 2007 for Atieh Bahar Group, a Tehran-based business consultancy founded by Khajehpour that helped foreign investors navigate the murky waters of Iran's heavily regulated and opaque economy, as well as providing expertise to Iranian business schools.
Their clients included Western oil majors such as BP, Shell and Statoil, as well as industrial corporations such as Siemens and Toyota.
In the 1990s, after reformist Mohammad Khatami was elected president, Namazi and a U.S.-Iranian friend, Trita Parsi, who now heads the pro-dialogue National Iranian American Council, authored a report on how dual nationals could help overcome decades of suspicion between Washington and Tehran.
In 2009, Khajehpour was arrested by the Revolutionary Guards Intelligence Corps on his return to Iran from Europe in the midst of protests against the alleged rigging of the re-election of then President Mahmoud Ahmadinejad.
Although he took no part in those protests, Khajehpour was held for more than three months in Evin on accusations of espionage before being released on bail and eventually leaving the country.
Namazi sold his shares in Atieh Bahar in 2007 and it is not clear whether his arrest is connected to Khajehpour's case.
The deal between Iran and major powers, signed in Vienna last July, was officially implemented on Jan. 16 after the International Atomic Energy Agency declared Tehran had curbed its nuclear program.
A few days after the signing, Namazi was stopped at Tehran Airport on July 18 when trying to fly back to Dubai after visiting his parents, relatives say. Revolutionary Guards took his passport and showed him a warrant saying he would be called in for investigation.
He was interrogated several times between July and Oct. 14, when he was taken to Evin prison. At the time of his arrest, he was working for Dubai-based Crescent Petroleum, but he told friends the questioning centered on his connections with U.S. institutions and with other WEF Young Global Leaders.
Secret negotiations on the prisoner swap involving Washington Post journalist Jason Rezaian and others were well advanced by the time he was detained.
Namazi is not the only dual national being held in apparent connection with Iran's power struggles. Bahman Daroshafaei, a former BBC Persian service journalist, was detained in Tehran last week, according to the opposition website Kaleme.com. His family was told on Saturday that he too was in Evin prison.
Opposition activists have suggested that Daroshafaei's arrest, on the eve of the first visit to Britain by an Iranian foreign minister in 12 years, might have been orchestrated by hardliners to thwart an improvement in relations.
Another Iranian-British citizen, Kamal Foroughi, remains in detention after being arrested in 2011 while working in Tehran as a business consultant.
Additional reporting by Parisa Hafezi in Ankara; editing by David Stamp