Washington ? An American who was among four Christian activists kidnapped last year in Iraq has been killed, a State Department spokesman said Friday.

The FBI verified that a body found Friday morning in Iraq was that of Tom Fox, 54, of Clear Brook, Va., spokesman Noel Clay said. He said he had no information on the other three hostages.

Clay said he did not know how Fox was killed but said additional forensics will be done in the United States. The U.S. 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’s organization, Christian Peacemaker Teams, said Friday, “We mourn the loss of Tom Fox, who combined a lightness of spirit, a firm opposition to all oppression and the recognition of God in everyone.”

Christian Peacemaker co-directors Doug Pritchard and Carol Rose said in a statement, “In response to Tom’s passing, we ask that everyone set aside inclinations to vilify or demonize others, no matter what they have done.”

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 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 U.S. and Iraqi prisons. No deadline was set.

Iraqi and Western security officials repeatedly warned the activists before their abduction that they were taking a grave risk by traveling in Baghdad without bodyguards.