MOSUL, Iraq -- As priests do everywhere, Archbishop Paulos Faraj Rahho, the leader of the Chaldean Catholics in this ancient city, gathered alms at Sunday Mass. But for years the money, a crumpled pile of multicolored Iraqi dinars, went into an envelope and then into the hand of a man who had threatened to kill him and his entire congregation.

"What else could he do?" asked Ghazi Rahho, a cousin of the archbishop. "He tried to protect the Christian people."

But American military officials now say that as security began to improve around Iraq last year, Archbishop Rahho, 65, stopped paying the protection money, one sliver of the frightening larger shadow of violence and persecution that has forced hundreds of thousands of Christians from Iraq. That decision, the officials say, may be why he was kidnapped in February.

Two weeks later, his body was found in a shallow grave outside Mosul, the biblical city of Nineveh.

Archbishop Rahho was among the highest-profile Iraqi Christians to die in the war. He was mourned by President Bush and Pope Benedict XVI before his role as a conduit for protection money paid by the Chaldean Christians to insurgents became known outside Iraq.

These payments, American military officials and Iraqi Christians say, peaked from 2005 to 2007 and grew into a source of financing for the insurgency. They thus became a secret, shameful and extraordinary complication in the lives of Iraq's Christians and their leaders -- one that Christians are only now talking about more openly, with violence much lower than in the first years of the war.

"People deny it, people say it's too complex, and nobody in the international community does anything about it," said Canon Andrew White, the Anglican vicar of Baghdad. Complicating the issue further, he said, some of the protection money came from funds donated by Christians abroad to help their fellow Christians in Iraq.

Yonadam Kanna, a Christian lawmaker in Iraq's Parliament, said, "All Iraqi Christians paid."

For more than 1,000 years, northern Iraq has been shared by people who for the most part believe and worship differently: Turkmen, Kurds, Yazidis, Sunni and Shiite Arabs, and Assyrian Christians -- of whom the Chaldeans are the largest denomination. (The Chaldean Church, an Eastern Rite church, is part of the Roman Catholic Church, but maintains its own customs and liturgy.)

Since the time of the Prophet Muhammad, the founder of Islam, Muslims in the Middle East permitted that diversity in part through a special tax on Jews and Christians. The tax was called a jizya -- and that is the name with which the insurgents chose to cloak extortion, Mafia-style, from Christians.

Officials say the demands could be hundreds of dollars a month per male member of a household. In many cases, Christian families drained their life savings and went into debt to make the payments. Insurgents also raised money by kidnapping priests. The ransoms, often paid by the congregations, typically ran as high as $150,000, several priests and lay Christians said.

In a paradox, this city, long the seat of Iraqi Christianity, also became known as the last urban stronghold of Sunni insurgents. Another, more painful, paradox is that many of Iraq's remaining 700,000 Christians paid to save their lives, knowing full well that the money would be used for bombs and other weapons to kill others.

Archbishop Rahho was a man of God who preached peace in his sermons. How he was contorted into fulfilling the role of providing payments to the insurgents is a complex question. Part of the answer lies in the deteriorating local politics of northern Iraq under the American occupation.

The north, in all its ethnic and religious diversity, was at first calm. But a 2004 Marine assault on Falluja, west of Baghdad, forced leaders of the Sunni insurgent group Al Qaeda in Mesopotamia to move north. The region then crumbled into terrifying mayhem. Christians, seen as allied with the American invaders, became targets of retributive attacks. "Leave or die" notes began appearing on their doorsteps.

"Anytime the Western countries go to war in the Middle East, it becomes a religious war," said Rosie Malek-Yonan, the author of "The Crimson Field," a historical novel depicting the 1914-18 massacre of Assyrians during World War I under similar circumstances.

Ms. Malek-Yonan, who testified on the issue of Christians' safety in Iraq at a Congressional hearing in 2006, accused the United States Army of failing to protect the Christians out of concern that special attention to this minority would play into the hands of insurgent propagandists.

Instead, the task of protecting Christian neighborhoods in Mosul and villages on the surrounding Nineveh Plain fell to the Kurdish pesh merga militia and, later, to Kurdish-dominated units of the Iraqi Army.

The Kurds, however, have their own agenda: expanding the borders of their region. The Kurds claim five disputed districts in Nineveh Province, including two that were historically Christian.

Ms. Malek-Yonan and other Assyrian Christians and experts accuse Kurdish commanders of depriving the Christians of security in an effort to tilt the demographics in favor of Kurds. The expected result, she said, was an exodus of hundreds of thousands of Christians from Iraq. At least hundreds have been killed. One priest was quartered and beheaded.

Kurdish officials deny that they failed to protect Christians. "The Kurdish Iraqi forces in Mosul do their job without differentiation between sects, religion or nationality," said Mohammad Ihsan, a minister for extra-regional affairs in the Kurdistan Regional Government.

Still, the Christian population of Iraq has fallen to roughly 700,000 today from a prewar estimate of 1.3 million.

Those who stayed behind faced an agonizing moral choice.

What was called the jizya was collected and paid by Jewish and Christian leaders to the insurgents operating on the west bank of the Tigris River. Archbishop Rahho, according to Mr. Kanna, the Christian lawmaker, made the payments on behalf of the Christians living in eastern neighborhoods of Mosul. He would have been an obvious choice: he had spent nearly his entire life in Mosul and was well known.

"He was the link," Mr. Kanna said.

The archbishop's cousin, Mr. Rahho, characterized the role as less central and emphasized the life-and-death nature of the choice to pay to save the lives of the parishioners. And the archbishop was certainly not the only person paying.

"We all paid," said one Assyrian Orthodox Christian priest here who spoke on the condition of anonymity for fear of retribution from insurgents. "We were afraid."

By several accounts by Christians who paid, the money changed hands quietly, according to a simple mechanism.

A man who introduced himself as Abu Huraitha, and who sometimes said he represented Al Qaeda in Mesopotamia, made the menacing phone calls, the Assyrian priest said.

"He said: 'I need money, I need money. If you do not give us money, I will kill you,' " the priest said. The bagman, however, was a fellow Christian, an elderly blue-eyed man who made the rounds of churches for the insurgents, the priest said. "If you do not give to him, they kill you."

He said he paid 10 million Iraqi dinars, or about $8,000, over three years, until last winter, when the United States Army reinforced its garrison in Mosul with the Third Armored Cavalry Regiment. Military operations increased in the city. The American units built neighborhood forts and traffic control points that disrupted the insurgents' movements. The racket started to fall apart.

During the fighting last winter, the Assyrian priest said, word trickled out that the Americans had killed Abu Huraitha. Many church leaders used the death of this contact to halt payments. Among them, perhaps most prominently, was Archbishop Rahho. He gave a speech on television in January denouncing the payments and saying that they should no longer be made.

A month later, on Feb. 29, he was kidnapped by gunmen after praying at the Holy Spirit Cathedral. They shot and killed his driver and two guards and bundled him into the trunk of a car. In the darkness, he managed to reach his cellphone and call his church. He implored them not to pay a ransom that would finance violence, church officials said.

Lt. Col. Eric R. Price, an adviser to the Iraqi Army units in eastern Mosul, said Archbishop Rahho, a diabetic, probably died from lack of medication before his release could be negotiated.

An Arab man, Ahmed Ali Ahmed, whom the Iraqi authorities identified as a member of Al Qaeda in Mesopotamia, the homegrown group that American intelligence says is led by foreigners, was captured, tried and sentenced to death for the kidnapping, though Mr. Kanna, the Christian lawmaker, said that Mr. Ahmed was only the man who carried out the kidnapping and that the organizers remained unpunished.

In fact, the church had been approached about ransom payments. The price demanded, but never paid, was $1 million and then $2 million.

By Andrew E. Kramer
New York Times