Archbishop Paulos Faraj Rahho of the Chaldean Catholic Church disappeared soon after Mass in Mosul on February 29. His driver and two bodyguards were killed in the attack on his car.
Kidnappers demanded a ransom of up to $3 million for his release, church sources said. Catholic leaders in Iraq found the archbishop's body on March 13, buried under a thin layer of dirt, after the kidnappers called a church official to say where they had left him.
The kidnappers claimed he had died on Wednesday, but local police said the body had started to decompose, implying the archbishop had been dead for several days.
Monsignor Shlemon Warduni, the auxiliary bishop of Baghdad, told reporters: "Monsignor Rahho is dead. We have found him lifeless near Mosul."
Pope Benedict XVI said in a message to the head of the Chaldean Church he was deeply pained by the news, and called the abduction an "an act of inhuman violence that offends the dignity of the human being and harms the peaceful coexistence of the dear Iraqi people."
The Chaldeans are aligned with the Roman Catholic Church and recognize the authority of the pope. The 550,000 Chaldean Catholics are the largest Christian community in Iraq. An estimated 60,000 Christians fled the country after 2003, when they became targets for Islamist extremists.