Terror leader Abu Musab al-Zarqawi (search) was most likely the man who beheaded Nicholas Berg, the American citizen whose execution was captured on videotape and shown on an Islamic Web site, U.S. intelligence and military officials said Thursday.
Despite the poor quality of the digitized audio and video of the tape that has been circulating since it first appeared Tuesday, officials said an initial technical analysis concluded that there was a "high probability" Berg's killer was the notorious al-Zarqawi.
A more detailed study of the videotape is being done, intelligence officials said.
"All indications are that is the case," said Lt. Gen. Ricardo Sanchez (search), the No. 2 U.S. military leader in Iraq. Asked whether he meant Zarqawi personally carried out the execution, Sanchez said, "All indications are he did it."
Asked about Zarqawi's whereabouts, the general said, "We believe he's moving around the country."
Berg's body was found in Baghdad on Saturday.
Meanwhile, sources close to the situation told Fox News that there was a "coincidental" link between Berg and accused Sept. 11 conspirator Zacarias Moussaoui (search).
FBI agents interviewed Berg a few years ago when they were investigating the Sept. 11 terrorist attacks on New York and Washington, the sources said. He was interviewed because, unbeknownst to him, Moussaoui had used his e-mail account when he was in Oklahoma.
Berg attended the University of Oklahoma and Moussaoui first settled in Norman, Okla., when he came to the U.S. The accused co-conspirator used at least one of the university's computers to communicate online, according to the sources.
The sources said that the FBI concluded that Berg had innocently given his e-mail account to someone and it had landed in the hands of other people, including Moussaoui.
On Tuesday, an Islamic Web site released the video showing Berg's beheading, titled "Sheikh Abu Musab al-Zarqawi slaughters an American infidel with his own hands."
The person shown speaking in the video — determined to be al-Zarqawi — wears a head scarf and a ski mask and is then shown on the video decapitating Berg, the official said. The speaker reads a lengthy statement criticizing Islamic scholars and taunting the crusaders.
Standing alongside four other militants wearing head scarves and masks to disguise themselves, al-Zarqawi then kills Berg.
Al-Zarqawi is thought to be in Iraq, operating his own terrorist network, known simply as the "Zarqawi network." A specialist in poisons, he is thought to have extensive ties across the militant Islamic movement and is considered an ally of Usama bin Laden.
As recently as March, U.S. officials said al-Zarqawi's practice was not to make taped public pronouncements or take credit for attacks. However, in the last five weeks, he has increased his public profile with at least three recordings, including Berg's beheading.
Al-Zarqawi is believed to be behind well over a dozen high-profile attacks in Iraq, and many other acts of violence, which have killed hundreds.
The United States is offering a $10 million reward for information leading to his death or capture.
The Associated Press contributed to this report.