The killing Friday of Ayatollah Mohammed Baqir al-Hakim (search) in the holy city of Najaf (search) further complicates the race for power in post-Saddam Iraq, riven by religious turmoil and wide discontent with the U.S.-led occupation.
Al-Hakim, 64, was killed in the car bombing of Imam Ali mosque (search), Shiite Islam's holiest shrine in Iraq. He had returned to his native country May 10 after more than two decades in exile in neighboring Iran.
The bomb exploded during prayers. Al-Hakim had just delivered a sermon calling for Iraqi unity.
Before the U.S.-led invasion, he formed the Supreme Council for the Islamic Revolution in Iraq, one of the most prominent anti-Saddam groups. It has long advocated Islamic rule for Iraq.
Many had compared al-Hakim's return to that of Iran's Ayatollah Ruhollah Khomeini, who spent 14 years in exile in Iraq before returning to lead his country's 1979 Islamic revolution and head its clerical regime until his death in 1989.
In the days after the U.S.-led war, Al-Hakim's group quickly established itself as the largest and best-organized Shiite movement in Shiite-majority Iraq.
The group set off alarm bells in Washington because of its strong links to Iran. While al-Hakim had repeatedly rejected religious extremism, he also denounced the notion of any foreign-installed government ruling Iraq's fractious population.
On his return to Iraq, al-Hakim denounced the U.S.-led occupation forces. He demanded they withdraw and allow the country's people to establish their own government -- one Islamic in nature.
"We don't fear these (U.S. and British) forces. This nation wants to preserve its independence and the coalition forces must leave this country," al-Hakim said on May 12.
Still, a brother of the ayatollah, Abdel-Aziz al-Hakim, is a member of the U.S.-backed Iraqi Governing Council, demonstrating the willingness of the Supreme Council for the Islamic Revolution in Iraq to work with the Americans -- at least for now -- while more radical Shiites have shown less patience.
The Al-Hakims are one of the most influential families in the Shiite community in Iraq.
Followers of the Shiite sect of Islam, a minority in the Islamic world, are a 60 percent majority in Iraq and also the majority in neighboring Iran.
Shiites long lived under the persecution and oppression of Saddam's Sunni Muslim-dominated regime, and Al-Hakim's return was seen by many as a forerunner to a Shiite political revival in Iraq.
Yet as the Americans launched their assault on Saddam's forces, Shiite leaders were also being targeted in Iraq.
Younger Shiites, many from Baghdad's Sadr City slum, have conducted an ongoing power struggle with the more traditional Shiite Muslims in the city and region, conducting a political battle to grab control from the al-Hakim family.
In April, two prominent Shiite clerics were assassinated in Najaf -- killings widely perceived as part of an internal dispute among rival Shiite factions.
Last week, a relative of the ayatollah's and one of Iraq's most prominent Shiite clerics, Mohammed Saeed al-Hakim, was injured when a gas cylinder placed alongside the wall of his Najaf home exploded. Three guards were killed and 10 family members injured in the Aug. 24 bombing, which happened just after noon prayers.
Mohammed Saeed al-Hakim is one of three top Shiite leaders threatened with death by a rival Shiite cleric shortly after Saddam was toppled April 9.
Also, a day after Saddam's ouster, a mob in Najaf hacked to death a Shiite cleric who had just returned from exile.
Abdul Majid al-Khoei was killed when a meeting called to reconcile rival Shiite groups erupted into a melee -- also at the Imam Ali mosque.