An American who was among four peace activists kidnapped in Iraq last year has been found shot dead in Baghdad.
Fox had worked two years in Iraq
Tom Fox's body was found on Thursday in the affluent Mansour district, Iraqi police said. There were signs that he had been beaten before being killed.
Mr Fox was seized last November, along with Briton Norman Kember and Canadians James Loney and Harmeet Singh Sooden.
A video tape showing the other three men was released on Tuesday, but Mr Fox did not feature on it.
Mr Fox, 54, had been working with Iraqi human rights organisations for the past two years.
His parent organisation, Christian Peacemaker Teams, said it mourned his loss.
"Tom Fox... combined a lightness of spirit, a firm opposition to all oppression and the recognition of God in everyone," it said in a statement.
The organisation's co-directors, Doug Pritchard and Carol Rose, appealed to people to "set aside inclinations to vilify or demonise others, no matter what they have done".
UK Foreign Secretary Jack Straw said he was saddened by the news and remained very concerned about the fate of the other hostages.
"This clearly raises the anxiety about the other hostages and we have been in contact with Mr Kember's family."
Cause of death unclear
US state department spokesman Noel Clay said the body had been identified as that of Mr Fox by the FBI.
TIMELINE OF ABDUCTION
26 November: Tom Fox and three other peace workers abducted
30 November: Video footage of the hostages aired on al-Jazeera
2 December: Second video of the hostages aired. Their captors threaten to kill them unless their demands are met by 8 December
8 December: Third video is aired on al-Jazeera showing Tom Fox and UK hostage Norman Kember wearing orange jumpsuits, blindfolded and shackled. The captors' deadline is extended to 10 December
28 January: New video of hostages, dated 21 January, aired on al-Jazeera
5 March: Vigils are held to mark 100 days since the kidnappings
7 March: New video of three of the hostages, dated 28 February, aired on al-Jazeera - Tom Fox does not appear on the tape
10 March: Tom Fox confirmed dead
"While additional forensics will be completed in the United States, they believe this is the body of Tom Fox.
"The family has been notified and our heartfelt condolences go out to the family."
Mr Clay added that it was not immediately known how Mr Fox had died.
Iraqi security officials said on Saturday that his body had been found with his hands tied, and injuries to the back.
The four men were travelling with Canadian-based international peace group Christian Peacemaker Teams when they were seized by a group calling itself the Swords of Truth.
Mr Fox, 54, came from Clearbrook, Virginia, and had two children.
After seizing the four, the kidnappers demanded the release of all prisoners being held in Iraq, and have so far released four videos of the hostages.
However, Mr Fox did not appear on the last one, which was shown by al-Jazeera TV on Tuesday, and dated 28 February.
The silent video appeared to show the other three men pleading for their governments to secure their release.
There has been no further word on the condition or whereabouts of the remaining three hostages.
British Muslim spokesman Anas al Tikriti told the BBC the news of Mr Fox's death came as a serious blow to the hopes of securing the release of the others.
"We were hoping in light of the fact that wave after wave of detainees were being released that maybe the abductors would see that in a good way and hopefully release the hostages."