Iraqi forces and the U.S. military have detained a number of suspects in the abduction and suspected murder of British aid worker Margaret Hassan.
They also found some of her belongings during Sunday's raid, including a handbag, ID and clothing, Iraqi police said.
The joint operation was carried out south of Baghdad near the town Madaen, the scene of frequent violence in recent weeks.
The director of CARE international in Iraq, who held Irish and Iraqi citizenship, was abducted in Baghdad on Oct. 19 on her way to work.
On Nov. 16, Arab satellite channel Al-Jazeera said it had received video footage showing the shooting of a blindfolded woman believed to be Hassan. The British embassy in Baghdad said the tape appearing to show her murder was probably genuine.
No group has claimed responsibility for her kidnapping and her body has never been found.
Hassan, 59, was born in Dublin and brought up in England. She had lived in Iraq for 30 years and was married to an Iraqi. She had been director of CARE international in Iraq for 12 years.
Meanwhile, an Australian citizen and engineer who's married to an American, has been kidnapped.
In a videotape released to the media on Sunday, Douglas Wood, 63, pleaded with U.S., British and Australian leaders to withdraw their troops from Iraq.
In the tape, Wood was guarded by militants who pointed guns at him. The tape included a sign identifying the Shura Council of the Mujahedeen of Iraq.
Australian Prime Minister John Howard said his government will do all it can to help free Wood, but he will not give in to the demands of terrorists.
"We will continue to do all we can, consistent with our position of not giving in to hostage-takers," Howard said. "We can't alter that position and we won't alter that position.
"We can't have the foreign policy of this country dictated by terrorists but we have got to do everything we can nonetheless to assist this poor man."