Peter Kassig, who changed his first name to Abdul-Rahman when he converted to Islam, is shown with a truck filled with aid supplies for Syrian refugees. Courtesy of Kassig family hide caption

toggle caption Courtesy of Kassig family

Abdul-Rahman Kassig, who was formerly known as Peter, is shown with a truck filled with aid supplies for Syrian refugees. The American aid worker was seized by the Islamic State in October 2013 and was killed by the group, which released a video Sunday of his beheading. Courtesy of Kassig Family hide caption

toggle caption Courtesy of Kassig Family