An American-Iranian pastor imprisoned in Tehran since September may face hanging because of his Christian faith, the Washington Free Beacon reports. Saeed Abedini sent a letter to his family Jan. 10 detailing his torture and treatment by Iranian authorities, and the U.S. State Department expressed "serious concerns" about his situation on Friday. Jordan Sekulow of the American Center for Law and Justice said: "This is an extremely critical time for American pastor Saeed and his family. We now know with certainty, from his own words, the brutality and life-threatening danger he faces in Iran's notorious Evin Prison. In a powerful letter from him released to family members in Tehran, Pastor Saeed reveals that he is undergoing beatings and is being told that he 'will hang' for his Christian faith. That treatment combined with the recent news that Pastor Saeed's case has been turned over to one of Iran's 'hanging judges' makes his circumstances more dire than ever." Abedini became an American citizen in 2010 after marrying his American wife, Naghmeh, but the Iranian government does not recognize his American citizenship, though it had enabled him to travel freely between both countries until this past summer. That's when he was pulled off a bus by authorities and placed under house arrest, then imprisoned and charged with several crimes that have not been made public -- but it is widely believed to be because of his Christian faith.