The man now known to the world as the head of al-Qaeda in Iraq was born Ahmad Khalayleh on October 30, 1966, in a traditional, pious household in the kingdom of Jordan.

Today Abu Musab al-Zarqawi espouses a ruthless perversion of the Islamic faith that he uses to justify beheading hostages and mass killings, but as a boy he was not interested in religion. He annoyed his father, Fadel, a retired soldier and tribal elder, by covering his arms in green tattoos, drinking alcohol and getting into fights. He was once arrested for drugs possession.

He appeared to be heading for a career as a small-time crook, but in the mid 1980s he - like thousands of other young Arab men - followed the Jihadi route to join the Mujahidin in Afghanistan fighting the Soviet Army. Surrounded by Islamists and hardened fighters, he changed.

He went home in 1991 and got a job in the town maintenance department, but within months he had fallen under the spell of an extremist Palestinian-born cleric of Abu Muhammed al-Maqdisi and his terror group, and became a religious zealot.

In 1995 he was jailed for 15 years on treason charges. In prison, he became radicalised and recruited fellow inmates to his cause.

On his release under royal amnesty in 1999, he was accused of plotting to kill US and Israeli tourists. Sentenced to death, he fled his homeland, leaving behind his wife, Um Muhammad. He has never returned, but reportedly continues to rule the household from afar, banning his four children from going to school and watching television. He has married for a second time.

He travelled to Afghanistan, then under the control of the Taliban, and in 2000 he set up a training camp in Herat. In 2001 he reportedly received £20,000 from al-Qaeda to set up links with the Ansar al-Islam group in northern Iraq.

It is not the first time that al-Zarqawi has been injured by Americans. A US missile strike in 2002 caused him a leg injury from which it is believed he still suffers.

During the two years since the US invasion of Iraq in March 2003, al-Zarqawi has forged a reputation for dispensing death and defying the West.

In August 2003 he was accused of orchestrating the devastating bombings of the UN headquarters in Baghdad, which caused the UN to pull out of Iraq.

In the same month his men bombed the Imam Ali mosque in Najaf, holy to Shia Muslims, killing 105 people. In November, his group - then called Tawhid and Jihad (Unification and Holy War) - detonated explosives at an Italian police HQ, in which 30 people died.

In February 2004 the CIA said it had proof of his al-Qaeda links, publishing a letter in which al-Zarqawi apparently asked bin Laden for help in turning Sunni Muslims against the despised Shia majority in Iraq to ignite a civil war.

The following month he was accused of killing 171 Shia pilgrims in co-ordinated bombings in Baghdad and at the shrine in Kerbala, and in April 2004 he was credited with organising the town of Fallujah's resistance to US forces.

In May, his group struck on the tactic of kidnapping Westerners, and released video showing al-Zarqawi personally beheading Nick Berg, a US telecoms contractor - the first in a grim toll of hostages murdered by his group, including a South Korean man in June, a Bulgarian hostage in July, and three Turkish truck drivers soon after.

The US responded by raising the price on his head, and sending bombers again and again to attack suspected al-Zarqawi hideouts in Fallujah. A master at manipulating the Western media, he showed his disdain each time by appearing on video straight afterwards to claim another atrocity.

Meanwhile al-Zarqawi's recruits - said to number only a few hundred, but continually refreshed with new blood as his bloody successes have attracted young Muslim firebrands from all over the Middle East and North Africa - had developed a new tactic, launching suicide car bomb attacks on Iraqi police recruiting lines. More than a thousand have people have died as a result, mostly young Iraqi men desperate for a job but also including many innocent bystanders.

The group has also increasingly targeted Iraq's fledgling political institutions. Before parliamentary elections it focused its attentions on Iraq's interim Governing Council. In May 2004 it succeeded in killing the council's head.

Since the elections, the group has claimed responsibility for murdering a woman member of the National Assembly, who was gunned down on the doorstep of her brother's home. It has also claimed many of the other atrocities that followed the formation of Iraq's first government last month, in an attempt to derail the political process.

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