After a tense night filled with stops and starts, lawyers helping to win reporter Jason Rezaian’s release from an Iranian prison learned Sunday that their year-and-a-half- long effort had finally come to an end.

The Washington Post correspondent, who had been imprisoned for 544 days, was released along with four other Americans in a prisoner exchange involving seven Iranians held in the U.S. The deal unfolded amid easing diplomatic relations between the two countries, as the U.S. determined that Iran held up its end of a nuclear deal and lifted economic sanctions against the country.