An American who was among four Christian activists kidnapped last year in Iraq has been killed, a State Department spokesman said. The FBI verified that a body found in Iraq Friday morning was that of Tom Fox, 54, spokesman Noel Clay said. He said he had no information on the other three hostages. Clay said additional forensics will be done in the United States. The US Embassy in Baghdad is investigating, he said. Fox's family has been notified, Clay said, and "our heartfelt condolences go out to them." "The State Department continues to call for the unconditional release of all other hostages" in Iraq, the spokesman said. Fox was the one American among four Christian Peacemaker activists kidnapped last year in Iraq. On Tuesday, Al-Jazeera television aired footage of the three other activists purportedly appealing to their governments to secure their release. The hostages seen in the brief video dated Feb. 28 were Canadians James Loney, 41, and Harmeet Singh Sooden, 32; and Briton Norman Kember, 74. Allan Slater, a Canadian member of Christian Peacemaker Teams, said at the time that he was disturbed not to see Fox. "We certainly are hopeful when we see three of our friends alive, but also it's very distressing that we didn't see Tom Fox, and I wouldn't want to hide that because I'm sure it's very distressful for Tom's family and friends as well," Slater told The Canadian Press from Baghdad. The previously unknown Swords of Righteousness Brigades claimed responsibility for kidnapping the four workers, who disappeared Nov. 26. The four had not been heard from since a videotape aired by Al-Jazeera on Jan. 28, dated from a week before. A statement reportedly accompanying that tape said the hostages would be killed unless all Iraqi prisoners were released from US and Iraqi prisons. No deadline was set.