On Sunday, after a delay, Washington Post reporter Jason Rezaian and two other Americans, released by Iran as part of a prisoner exchange deal, left Tehran on an airplane, the Post reports. The fourth American prisoner, whose detention seems not to have been reported before yesterday, did not join them.

Whether Nosratollah ­Khosravi-Roodsari, about whom practically nothing is known—he has only been described as a “businessman”—intended to remain in Iran, or was simply traveling separately, is unclear.

“We can confirm that our detained U.S. citizens have been released and that those who wished to depart Iran have left,” a senior administration official told the Post. (Reuters has a similar quote.)

“We have no further information to share at this time and would ask that everyone respect the privacy of these individuals and their families.”

Update – 12:10 pm

White House officials tell ABC’s Alex Mallin that they don’t know if Khosravi-Roodsari plans to leave Iran: “It’s his free determination where he wants to go.”

Photo via AP Images. Contact the author of this post: brendan.oconnor@gawker.com.