Shane Bauer, who lives in Damascus, is a freelance journalist who was excited about reporting from Iraqi Kurdistan. Shourd, Bauer's girlfriend, is a teacher and travel writer.
Joshua Fattal arranges trips for foreign exchange students, and his family has roots in Iraq.
A fourth member of the group, Shon Meckfessel, did not feel well and had stayed behind at the hotel instead of going on the hike.
On July 31 Meckfessel received a phone call from Bauer telling him they were surrounded by armed men and being taken into custody.
Meckfessel says his friends did not intentionally cross into Iran.
"There is no 'Lonely Planet Iraqi Kurdistan,'" Meckfessel wrote in a statement, referring to the popular travel guidebooks. "I hope that people understand my friends' presence in the area for what it was: a simple and very regrettable mistake."