The alleged killing of the family was said to have taken place at their home in the town of Al-Mahmudiyah.
No charges have been filed.
It is the latest in a series of investigations in which U.S. forces have been suspected of killing Iraqi civilians. At least 14 U.S. troops have been convicted.
The United States also is investigating allegations that two dozen unarmed Iraqi civilians were killed by U.S. Marines in the western town of Al-Hadithah on November 19 in a revenge attack after a Marine died in a roadside bombing.
COALITION MEMBERS: In addition to the United States, 28 countries are Multi-National Force-Iraq (MNF-I) contributors as of May 31, 2006: Albania, Armenia, Australia, Azerbaijan, Bosnia-Herzegovina, Bulgaria, the Czech Republic, Denmark, El Salvador, Estonia, Georgia, Italy, Japan, Kazakhstan, Latvia, Lithuania, Macedonia, Moldova, Mongolia, the Netherlands, Poland, Portugal, Romania, Singapore, Slovakia, South Korea, Ukraine, and the United Kingdom. Fiji is participating as part of the UN mission in Iraq. Hungary, Iceland, Slovenia, and Turkey are NATO countries supporting Iraqi stability operations but are not part of MNF-I.
NON-U.S. MILITARY PERSONNEL IN IRAQ: United Kingdom, 8,000 as of May 26, 2006; South Korea, 3,237 as of May 9, 2006; Italy, 2,900 as of April 27, 2006; Poland, 900 as of May 30, 2006; Australia, 900 as of March 28, 2006; Georgia, 900 as of March 24, 2006; Romania, 860 as of April 27, 2006; Japan, 600 as of May 30, 2006; Denmark, 530 as of May 23, 2006; All others, 1,140.
(Source: The Washington-based Brooking Institution’s Iraq Index of June 15, 2006)
RADIO FREE IRAQ: To visit the Arab-language website of RFE/RL's Radio Free Iraq, click here.