The Iranian authorities use interrogation techniques such as intimidation, threats and blindfolding, said the husband of a detained American academic, and he is very worried that his wife could be subjected to these tactics. Shaul Bakhash, the husband of Haleh Esfandiari, who was charged with spying by Iranian authorities, said he has not spoken to his wife since her detention and is concerned about her mental and physical condition. She has been allowed to make phone calls to her mother in Tehran a few times a week, said her husband. He said that nothing of substance is discussed on the calls, and that despite the brevity of the calls, her mother looks forward to them every day. "Her mother in Tehran is ecstatic," said Bakhash. "She hangs on them so much." The colleagues of Esfandiari pleaded today for her release. "Haleh is innocent. She should be set free," said Lee Hamilton, director of the Woodrow Wilson Center where Esfandiari works. Esfandiari is one of four Americans currently detained in Iran. The others are Parnaz Azima, a Radio Farda journalist, Kian Tajbakhsh, a scholar with the Soros Foundation’s Open Society Institute, and Ali Shakeri, confirmed by the State Department for the first time today as being detained by Iranian authorities. Deputy State Department spokesman Tom Casey said the string of detentions are part of a "disturbing pattern." Esfandiari’s troubles began as she drove to the airport in Tehran to catch a flight back to her home in Washington, D.C., after visiting her ailing mother. According to her family, she was robbed at knifepoint by masked men who took her bags and passport. When she went to get a new passport, she was pulled aside at the passport office and subjected to lengthy interrogations by Iran’s Ministry of Intelligence. Those interrogations continued for several weeks. A Feb. 20 letter by Wilson Center Director Lee Hamilton to Iranian President Mahmoud Ahmadinejad requesting Esfandiari’s release was not answered. Do you have a tip for Brian Ross and the Investigative Team?