Senior German officials paid tribute at a memorial on Tuesday to two officers of the elite squad GSG-9 who were killed in Iraq in April. Tobias Retterath, 25, and Thomas Hafenecker, 38, were reported missing on April 7. They were travelling to Baghdad to provide security for the German Embassy when their convoy was ambushed near Fallujah. "They were aware of the risks, but they also knew how necessary this mission was," Interior Minister Otto Schily said during the memorial service held in Bonn. Authorities found Retterath's body three weeks after he went missing; they have yet to locate Hafenecker's body. "We are doing everything we can to ensure complete certainty about his fate," said Jürgen Chrobog, Germany's deputy foreign minister.