Inizi says he knows exactly who ordered the attack: a former colonel in Saddam Hussein’s secret police, the Mukhabarat. After the bombing, the officer promptly vanished from his Baghdad home, together with his wife and children. Inizi refuses to divulge the man’s name, saying only that Dawa is on his trail. The group’s leaders haven’t shared their leads with the Coalition, Inizi says: they want the U.S. forces out of Iraq–the sooner, the better. Hakim himself, in the early days of the occupation, had staked out a fairly accommodating position toward the Americans. But having spent more than a decade in exile as a favored guest of the Iranian government, he was hardly considered an American stooge.

Then why would the Baathists want Hakim dead? Perhaps to turn Iraq’s Shiite majority against itself and make the country ungovernable. The risk frightens many Shiite leaders. From outside, Iraq’s Shiites may look like one cohesive group, but from inside they’re a seething tangle of resentments and rivalries over money, power and prestige. Even the country’s highest-ranking cleric, Grand Ayatollah Ali Sistani, has less-than-absolute authority, despite the headaches he has given the Americans lately with demands for direct elections to create a new government. The Iranian-born Sistani, 73, shares power in Najaf with three other grand ayatollahs, who all seem convinced that religion should have only a very limited role in politics.

Some prominent Shiites in Iraq disagree vehemently. One of the most ambitious is a youthful Iraqi-born cleric named Moqtada Sadr, who maintains a large private militia, the Mahdi Army, and regularly preaches fire-and-brimstone anti-U.S. sermons in Al Kufah, just outside Najaf. The grudges between Sadr’s and Sistani’s followers date back many years. Even so, the two men’s representatives made a deal immediately after the regime’s collapse to share the pulpit at Karbala’s Imam Hussein Mosque, preaching there on alternate Fridays. Their truce lasted until August, when Sistani’s man barred Sadr’s representative from the mosque.

Things deteriorated from there. On Oct. 10, Sadr announced he was forming a national government. No one paid much attention. You can’t run a government without cash, and Sadr didn’t have it. Three nights later his followers fanned out across Karbala, taking over the post office and the local TV station. Then a group of about 50 armed men advanced toward the city’s two monumental shrines, where they were met by tribal security forces and townspeople loyal to Sistani. The vast courtyard between the shrines was filled with rocket-propelled grenades and AK-47 fire.

Iraqi police and Coalition forces sealed the city, fearing an influx of Sadr reinforcements. The fighting continued all night, and members of both camps say a third group joined in–probably Baathists, they say. By morning, 19 Iraqis were dead, including four police officers. “It wasn’t a confrontation about Islam,” says the Karbala Tribal Council’s secretary-general, Sheik Ali al Assadi. “It was about politics. Naturally, money was part of that.” Every year, Shiite pilgrims donate millions of dollars at the shrines that were at the center of the battle. The money is administered by the grand ayatollahs; junior clerics speculate wildly about the exact total.

Hakim’s assassination almost certainly helped set off the uprising. Four potential targets were named in Inizi’s warning: the ayatollah, his brother, their uncle (one of the four grand ayatollahs)–and Moqtada Sadr. The list spells nothing but trouble. The feud between the Hakim and Sadr families is a Babylonian version of the Hatfields and McCoys. “They’ve disliked each other for a long time,” says a young cleric over a cup of tea in Najaf. He turns and asks his senior, “Why do they dislike each other, again?” The old man waves him off. Senior clerics don’t discuss such things publicly.

Both families belong to the Iraqi Shiite aristocracy. But during Saddam’s rule, the Hakim brothers escaped to Iran. The Sadrs stayed in Iraq and were rewarded by Saddam, who appointed Sadr’s father, Ayatollah Mohammed Sadeq Sadr, as director of Najaf’s religious schools. As a result, the Sadrs dismiss the Hakims as “Iranian lackeys.” The Hakims respond by calling the Sadrs “Baathist lackeys.” Mohammed Sadeq Sadr was gunned down in 1999 after criticizing Saddam. Yet after the regime’s collapse, Moqtada tried to revive his father’s legacy. In May, Hakim came home from Tehran and headed straight for the pulpit of the Imam Ali Mosque, where Mohammed Sadeq Sadr used to preach. When that happened, some clerics say, Moqtada began hating Hakim even worse than he hates Americans.

The FBI, which calls the Hakim murder case “a high priority,” says Moqtada Sadr is “not our focus.” Most of his fellow clerics, no matter what they think of him personally, say they’re sure he had nothing to do with the bombing. Privately, though, they say someone on his payroll might have had a role without Sadr’s knowledge. “It’s been clearly proven that the office of Sadr was infiltrated by Baathists,” says a spokesman for one of the four grand ayatollahs. “Moqtada’s father tried to work with the regime and against it,” says Adel Abdel Mehdi, a senior official in the Hakims’ political party, the Supreme Council for the Islamic Revolution in Iraq. “This allowed a lot of Baathists in their movement. It’s important to get rid of them.”

An open war between Iraq’s Shiites would be a bloodbath. Sadr’s loosely organized Mahdi Army has several hundred core members, mostly from the Baghdad slums of Sadr City (the place took its name from his father). The Badr Brigade, led by the Hakims, has about 10 times that number, and their fighters have spent nearly two decades training with Iran’s Revolutionary Guard Corps. The grand ayatollahs have no militia of their own. They depend on the loyalty and good will of their followers. The question is whether that–together with a common hatred of the Sunni Baathists–will be enough to keep the peace.