U.S. troops arrested a relative of Izzat Ibrahim al-Douri (search), and believe he may help in the hunt for the most senior former regime figure still at large, a U.S. officer said Wednesday.

The man, who was not identified, was arrested late Tuesday in a raid in Tikrit, Saddam Hussein's (search) hometown, said Lt. Col. Steven Russell, who led the operation.

Russell described the suspect as a "close relative" of al-Douri, who was the vice chairman of the Baath Party's (search) Revolutionary Command Council and a longtime confidant of Saddam.

The suspect was arrested based on information received from a man soldiers had detained earlier Tuesday for possessing firearms, Russell said.

"We believe that he may have some useful information" in the hunt for al-Douri, Russell said. "The family he comes from has been harboring 'deck of cards' guys," he said, referring to the U.S. list of the 55 most wanted Iraqis.

Al-Douri, in his late 60s, is No. 6 on the wanted list. The United States has put a $10 million bounty on his head.

Late last year, al-Douri's wife and daughter were detained. In January, troops arrested four of his nephews who were suspected of helping him hide. All six are believed to remain in U.S. custody.

Since Saddam was arrested Dec. 13, al-Douri has taken on the title of the Pentagon's most wanted man in Iraq.

Nevertheless, it is unclear what role, if any, he is playing in the insurgency that continues to plague U.S. troops in areas north and west of Baghdad.

Last month, New York-based Human Rights Watch accused the U.S. military of kidnapping in its arrests of al-Douri's wife and daughter. The two women remain in U.S. custody even though they have not been charged.

"Detaining persons for the purpose of compelling actions from the opposing side amounts to hostage-taking, which is a grave breach of the Geneva Conventions -- in other words, a war crime," Human Rights Watch said.

In a letter to Defense Secretary Donald H. Rumsfeld, the group urged a halt to such tactics and asked him to ensure U.S. forces abide by the 1949 Geneva Conventions, holding soldiers accountable for ordering, condoning or carrying out serious violations of the laws of war.