It shows three men in military uniform, sitting on the ground with their hands bound behind their backs in a small concrete room with gunmen standing around them.

Under questioning, the men say they are members of the "Wolf Brigade," a special Iraqi police commando unit that Sunnis accuse of being a front for Shiite militiamen who kill Sunni Arabs.

Text in the video says the three were part of a "Shiite death squad" that kidnapped and killed Sunnis at checkpoints south of Baghdad in March and April. It says they were among 10 police commandos captured by Ansar al-Sunnah last month.

A militant off-camera asks them about the incident and other alleged slayings of Sunnis. The men reply in low voices, looking terrified. One mostly stares with his mouth hanging open.

"They (the Sunnis) were beheaded by those who took and detained them," one of the three says. Next the video shows the three captives lying on the ground outdoors. A militant sharpens a knife before he, with the help of others, beheads the men one by one.

At the end of the tape, the group warns Iraqis against joining the security forces: "Otherwise, you will live in terror until we eliminate you and your fate will be in hell."

Iraqi and U.S. leaders have acknowledged that al-Zarqawi's killing was not likely to stop the insurgency, now in its fourth year. But they hoped it would rob his supporters of an iconic figure around which they rallied.

The U.S. military has moved quickly to take advantage of the power vacuum left by al-Zarqawi's death, carrying out at least 56 raids since Wednesday's airstrike pulverized his hideout in a remote village northwest of Baghdad.

A search of the destroyed safe house yielded documents and electronic storage devices, all being assessed for potential use against his followers, a U.S. military officer has said.

Investigators also found documents and unspecified "media," which the officer indicated usually means information storage devices such as computer hard drives and digital cameras. The officer spoke on condition of anonymity because the search results have not been formally announced.

At the scene of the airstrike, a floral-pattern pillow, a torn mattress, sandals, and a red blanket lay scattered among the debris of concrete blocks and twisted steel, according to Associated Press Television News footage.

An air conditioner and part of a washing machine also could be seen in the area, where ripening pomegranates hung from a remaining tree. Pieces of women's clothing also were found in the rubble.

Beside al-Zarqawi, the airstrike also killed his spiritual adviser, two men, two women and a girl estimated between the ages of 5 and 7.