September 14, 2011 - A Western diplomat tells CNN that an Omani official is en route to Tehran to help negotiate the release of Josh Fattal and Shane Bauer. Oman helped secure the release of Sarah Shourd in 2010.
September 21, 2011 - Josh Fattal and Shane Bauer are released from prison on bail of $500,000 each and their sentences are commuted. Their lawyer declined to say who had paid the bail.
September 25, 2011 - Josh Fattal and Shane Bauer arrive back in the United States.
Saeed Abedini September 26, 2012 - According to the American Center for Law and Justice, Saeed Abedini, an American Christian pastor who was born in Iran and lives in Idaho, is detained in Iran. The group says that Abedini's charges stem from his conversion to Christianity from Islam 13 years ago and his activities with home churches in Iran.
January 2013 - Abedini is sentenced to eight years in prison, on charges of attempting to undermine the Iranian government.
Amir Mirzaei Hekmati December 17, 2011 - Iran's Intelligence Ministry claims to have arrested an Iranian-American working as a CIA agent, according to state-run Press TV.
December 18, 2011 - Iran's semi-official Fars news agency broadcasts a video in which a young man says his name is Amir Mirzaei Hekmati, and that he joined the U.S. Marine Corps and worked with Iraqi officers.
December 19, 2011 - The U.S. State Dept. confirms the identity of the man detained in Iran and calls for his immediate release.
December 20, 2011 - Hekmati's family says that Hekmati was arrested in August while visiting relatives in Iran. The family asserts that they remained quiet about the arrest at the urging of Iranian officials who promised his release.
December 27, 2011 - Hekmati's trial begins in Iran. Prosecutors accuse Hekmati of entering Iran with the intention of infiltrating the country's intelligence system in order to accuse Iran of involvement in terrorist activities, according to the Fars news agency.
January 9, 2012 - An Iranian news agency reports that Hekmati is convicted of "working for an enemy country," as well as membership in the CIA and "efforts to accuse Iran of involvement in terrorism." He is sentenced to death.
End of January 2012 - Behnaz Hekmati, Amir Hekmati's mother, travels to Iran alone and sees her son, according to sources close to the family.
March 5, 2012 - An Iranian court dismisses a lower court's death sentence for Hekmati and orders a retrial. Hekmati remains in prison.
September 2013 - In a letter to U.S. Secretary of State John Kerry, Hekmati says that his confession was obtained under duress.
Robert Levinson March 8, 2007 - According to his family, retired FBI agent Robert Levinson is last seen on Iran's Kish Island during a business trip.
June 1, 2007 - President George W. Bush says he is "disturbed" by the lack of information Iranian officials have provided on the case.
December 2007 - The Iranian government repeats that they do not know what happened to him.
2010 - Levinson's captors send a "proof of life" videotape and photographs of him to his family. The images are released to the public in 2011.
March 3, 2011 - Secretary of State Hillary Clinton says that evidence is growing that Levinson is alive and being held somewhere in southwest Asia.
January 8, 2013 - Bob Levinson's family releases photographs of Levinson wearing a jumpsuit and holding signs.
September 2013 - During an interview with CNN's Christiane Amanpour, Iranian President Hassan Rouhani says there is no news of Levinson but speaks of cooperation and gathering information to find his whereabouts.
Kenneth Bae December 11, 2012 - U.S. officials confirm that American citizen Kenneth Bae has been detained in North Korea for over a month.
April 30, 2013 - North Korea's Supreme Court sentences Bae to 15 years of hard labor for "hostile acts" against the country.
August 27, 2013 - The State Department says that Ambassador Robert King will travel to Pyongyang at North Korea's invitation and ask for Bae's pardon on humanitarian grounds.