When he was released, he fled to Europe, eventually returning to Afghanistan and running terrorist camps there. He is said to have specialized in poisons and chemical attacks.
Intelligence sources say al-Zarqawi was fighting against U.S. forces in Afghanistan when they began their campaign shortly after Sept. 11, 2001, and was wounded. They believe he fled to northern Iraq, where he reportedly associated with a group of Kurdish Islamic fundamentalists called Ansar al Islam, which U.S. officials have linked to al Qaeda.
Bin Laden appointed al-Zarqawi as his deputy in Iraq after the Jordanian pledged allegiance to him in October 2004, according to intelligence reports. Al-Zarqawi changed his group's name from Tawhid wal Jihad to Al Qaeda Organisation for holy war in Iraq. The United States immediately ordered a freeze on his assets.
In January 2005, the governor of Baghdad, Ali al-Haidri, was assassinated and in April, interim Prime Minister Iyad Allawi escaped an assassination attempt when a suicide bomber attacked his convoy near his home. Al-Zarqawi's group claimed responsibility for both attacks.
The attacks only escalated with the insurgency spearheading its efforts against the U.S. military but more specifically against Iraqi police forces. In February 2005, U.S. officials said they uncovered communications from bin Laden to al-Zarqawi.
In the communiqués, bin Laden "suggested" al-Zarqawi might be able to help al Qaeda by attacking inside the United States, a counterterrorism official said.
Two other sources said the information was actually delivered to al-Zarqawi by Ayman al-Zawahiri, bin Laden's deputy, but that the message was clearly from bin Laden. The communications did not mention any specific targets. And, the official cautioned: "Let's face it. Zarqawi has his hands full in Iraq right now." Indeed, one of his top lieutenants had been captured the week before.
But senior officials say it was a significant discovery -- and a clear message for al-Zarqawi to attack inside the United States.
A month later, Jordan's state security court sentenced him in absentia to 15 years in jail for a plot to attack the kingdom's embassy in Baghdad.
Meanwhile, al-Zarqawi stepped up his efforts to fight coalition forces in Iraq. In an audiotape allegedly from him, he called for more suicide attacks on U.S. forces and vowed not to let President Bush enjoy "peace of mind."