"The way I respond to the comments of the alleged Iraqi who saw what went on there is: 'that's baloney,'" Gen. George Casey said.
An Iraqi man who was one of the first people on the scene of the U.S. airstrike targeting al-Zarqawi said he saw American troops beating a man who had a beard like the al Qaeda leader.
Speaking on Fox News Sunday, Casey said al-Zarqawi died while American soldiers were attempting to save his life.
The witness, who lives near the house where al-Zarqawi spent his last days, said he saw the man lying on the ground near an irrigation canal. He was badly wounded but still alive, the man told Associated Press Television News.
The Iraqi, identified only as Mohammed, said residents put a bearded man in an ambulance before U.S. forces arrived.
"When the Americans arrived they took him out of the ambulance, they beat him on his stomach and wrapped his head with his dishdasha, then they stomped on his stomach and his chest until he died and blood came out of his nose," Mohammed said, without saying how he knew the man was dead.
No other witnesses have come forward to corroborate the Iraqi man's account that al-Zarqawi was beaten. U.S. officials have only said al-Zarqawi mumbled and tried to roll off a stretcher before dying.
U.S. authorities changed their initial account of the al Qaeda in Iraq leader's death, first saying he died outright in the airstrike, then saying he survived, but died soon after.
A U.S. military spokesman on Thursday said Iraqi police were first on the scene of the airstrike in Hibhib and then U.S. troops arrived. Maj. Gen. William Caldwell said that al-Zarqawi was conscious when U.S. forces found him and that he briefly struggled to get away. The Americans tried to provide medical treatment, but al-Zarqawi died shortly after.
Lt. Col. Thomas Fisher of the 1st Battalion, 68th Armored Cavalry said his men showed up at the site about five minutes after the blast and cordoned it off. He said a patrol was in the area already.
"We didn't know it was Zarqawi, we just knew it was a time-sensitive target," he said at the scene early Saturday. "We suspected who it was."
Al Qaeda in Iraq vowed on Sunday to carry out "major attacks," insisting in a Web statement that it was still powerful after the death of al-Zarqawi.
The statement did not name a successor to al-Zarqawi, but it said the group's leadership "renews its allegiance" to Osama bin Laden.
On Sunday, two U.S. military forensic specialists finished their autopsy on al-Zarqawi's remains, part of the investigation to reconstruct the last minutes of his life, the U.S. Command said.
"The autopsy is completed. However, we are not releasing results yet," Maj. William Willhoite said.
Caldwell, the spokesman for the U.S. military in Baghdad, said Saturday the decision to fly in forensic experts was made shortly after al-Zarqawi's death.
"I think if we don't do a full autopsy then that might irresponsible on our part," Caldwell said. "I think we sort of owe that just for this reason: How did he actually die?"
He said the U.S. government thought it was important enough "that we grabbed two people in the last 48 hours and told them pack up and move to Iraq."