Saeed Abedini, a naturalized US citizen who converted to Christianity, was arrested in September on a return visit to Iran and in a recent letter said he suffered beatings in prison, his wife and his US-based lawyer said.
His wife said that the 32-year-old will face charges of harming national security starting Monday at a trial under Abbas Pir-Abassi, a revolutionary court judge who has been criticized overseas for harsh verdicts.
Naghmeh Abedini voiced hope that international pressure would benefit her husband but said it was "highly possible that put under pressure (by Iran's leadership) they would give a very long sentence and possibly the death penalty."
State Department spokeswoman Victoria Nuland recently said the United States had "serious concerns" over the case and urged Iran to grant Abedini access to an attorney. His wife said he has not seen a lawyer since his arrest.
Iran's constitution following the 1979 Islamic revolution recognizes the rights of several religious minorities including Christians, but the regime has targeted former Muslims for leaving the faith.
Naghmeh Abedini said her husband, with whom she has two children, was detained in 2009 and released after an agreement not to engage in religious activities in Iran, such as working with underground churches.
She said that Saeed Abedini had returned nine times to Iran since 2009 and did not violate the agreement. She said he was building an orphanage near the northern city of Rasht out of a conviction that the Bible teaches helping widows and orphans.
"He had no worries that he would be arrested, believing that he kept his end of the promise and that the government would keep their end," she told AFP from the western state of Idaho.
Abedini said that the arrest showed an increasingly hard line in Iran. She quoted an interrogator as telling her husband that the regime was worried that "if the country is not following Islam, then we have less control over them.
"So in a way they connect people becoming Christian to politics," she said.
Jordan Sekulow, executive director of the American Center for Law and Justice, a conservative legal advocacy group that is representing Abedini, said the case illustrated an internal shift in Iran.
The case has moved from the jurisdiction of police and intelligence services under the control of Iran's president to a revolutionary court that reports to the nation's supreme leader, Ayatollah Ali Khamenei.
"That's going to be harsher and it's going to be more tense and it's going to be less restricted," Sekulow said of the revolutionary court. "They kind of can do as they want."
The American Center for Law and Justice said that 49 members of Congress have urged the State Department to press for Abedini's release, saying that the United States can do more to support him despite the absence of diplomatic relations with Iran.
The US Commission on International Religious Freedom, a panel that advises US policymakers, called on Iran to release Abedini "immediately and unconditionally."
"The national security charges leveled against Mr. Abedini are bogus and are a typical tactic by the Iranian government to masquerade the real reason for the charges: to suppress religious belief and activity of which the Iranian government does not approve," the commission's chair, Katrina Lantos Swett, said in a statement.