The first U.S. citizen to be killed by ISIS, James Foley was taken hostage in Syria in November 2012 and beheaded in August 2014. The 40-year old from Rochester, New Hampshire was an experienced war journalist who contributed videos to major media outlets including Agence France-Presse and GlobalPost. NICOLE TUNG/AFP/Getty Images
Also a freelance journalist, Steven Sotloff disappeared during a reporting trip in Syria in August 2013 and was beheaded a year later. The U.S.-Israeli citizen, who wrote for publications like Time, Foreign Policy and Christian Science Monitor, was when he died.
British national David Haines was abducted in March 2013 while working at a Syrian refugee camp for an aid group and executed a year later. The 44-year-old father of two had more than a decade of experience doing aid work providing logistics to Handicap International and as an unarmed peacekeeper with Nonviolent Peaceforce. Family photo
Originally a taxi driver from the UK, Alan Henning was volunteering to deliver food and water to people affected by the Syrian civil war. He traveled to the Middle East in December 2013, was taken hostage on Boxing Day and held for more than a year before being killed. Courtesy of family of Alan Henning
Peter Kassig, who served briefly as a U.S. Army Ranger, was working as a humanitarian worker in Syria when he was kidnapped on October 1, 2013 en route to deliver food and medical supplies. The 26-year old was confirmed dead after ISIS posted a video on November 16, 2014. KASSIG FAMILY/AFP/Getty images
Haruna Yukawa was a 42-year-old Japanese national who aspired to become a security contractor to Japanese companies in conflict zones. He was in the hands of ISIS for several months before a video released in January showed his killing.
A freelance journalist, 47-year-old Kenji Goto worked in Syria and other war-torn countries for numerous outlets including Japan's public broadcaster NHK. Goto was in Japan when news surfaced about the capture of Haruna Yukawa, who he had befriended while working in the region. Goto returned to Syria hoping to negotiate his release but was himself captured and later executed.
Royal Jordanian Air Force pilot Moath al-Kasasbeh went missing when his plane crashed during a December 2014 mission. A devout Muslim who memorized the Quran, the 27-year old was shown in an ISIS video in February where he was brutally burned alive. PETRA/Jordan State News
Kayla Mueller, was a 26-year-old humanitarian worker from Prescott, Arizona, who was taken hostage in August 2013 in Syria. Although the circumstances of her death are unclear, it was confirmed in February when ISIS sent a private message to her family. U.S. government officials later revealed that she had been tortured and sexually abused by ISIS' top leader Abu Bakr al Baghdadi during her captivity. Courtesy Mueller Family
Croatian national Tomislav Salopek was a topographer who was kidnapped in July while driving to work in Egypt, the Croatian foreign ministry said. In August, ISIS released a video showing his apparent beheading. The same month the group posted another video, showing the decapitated head and body of antiquities expert Khaled al-Asaad. The 82-year old, who dedicated his life to preserving cultural relics, was killed for not revealing the location of ancient treasures. From LinkedIn