Four people have been arrested for the Nick Berg beheading, AP reports. Not Zarqawi or other al-Qaeda allies -- these guys are Fedayeen Saddam:

Four people have been detained in the killing of American Nicholas Berg, whose decapitation was captured on videotape, an Iraqi security official and a U.S. military official said Friday. The Iraqi official said the group that killed Berg was led by a relative of Saddam Hussein.

The suspects were former members of Saddam Hussein's Fedayeen paramilitary organization, the Iraqi security official said on condition of anonymity....

Well, that suggests a simple explanation for why the blade-wielder in the video said he was Zarqawi but wore a mask: Maybe he was a Saddam loyalist trying to pin the blame on another group.

(Another possibility, I guess, is that the Iraqi police are rounding up the usual suspects.)

(Of course, folks like William Safire are going to reach yet another conclusion: See? Zarqawi claimed responsibility -- and Saddam loyalists were arrested! They're working together! Told ya! Baathists = jihadists! Saddam = 9/11! Q.E.D.! Sigh.)

The alleged ringleader is named in the AP story:

The group that was involved in the killing of Berg was led by Yasser al-Sabawi, a nephew of Saddam Hussein, the Iraqi security official said....

Al-Sabawi was not among those arrested, the Iraqi official said.

I Googled Al-Sabawi and all I found was this, from April 29, 2004:

CPA Releases Former Regime ‘Criminals’

(Al-Adala) -- The Coalition Provisional Authority (CPA) has freed some criminal of the former regime. They include former Minister of Interior Sameer al-Sheikhli, former head of intelligence Sadoon Shakir, and former private security officer and [sic] Yasir al-Sabawi. Also released were other symbols of the old regime like the former head of security office and some high ranking police and army officers. Some of the freed men immediately fled to Syria, close sources said.

So did we let this guy go mere days before he and/or his associates killed Berg?