BAGHDAD - Iraqi security forces have arrested five Americans in connection with the killing of a contractor last month in Baghdad's Green Zone, Iraqi officials said Sunday. It could be the first case in which Americans face local justice under a security pact signed last year.

The Americans were detained Wednesday, although U.S. and Iraqi officials say no charges have been filed. James Fennell, a U.S. Embassy spokesman, said Sunday that consular officials had visited the men a day after their arrest to make sure "they're being afforded their rights under Iraqi law."

"The men appeared well," he said.

Maj. Gen. Abdul-Karim Khalaf, a spokesman for the Interior Ministry, said the men were being held at a police station in the Green Zone as part of a joint U.S.-Iraqi investigation. He said FBI agents had provided a tip to Iraqi forces, then accompanied them on a raid at a house where they had uncovered weapons and drugs.

But there were conflicting accounts about the arrest and possible charges.

Fennell said the men were not arrested on suspicion of involvement in the murder of Jim Kitterman, a 60-year-old contractor from Houston. During a search of the men's house, authorities found "possible evidence on an unrelated matter," he said, without disclosing details.

Khalaf and Alaa al-Ta'i, an adviser to the interior minister, said that although the men had not been charged, they were indeed being held as suspects in Kitterman's death. Two other Iraqi officials said that only two men were being held in regard to the killing.

Kitterman's body was found in the heavily fortified Green Zone on May 22. He had been blindfolded and stabbed, and his hands were bound.

A U.S. official in Baghdad had said that a preliminary investigation into his death suggested that it was a crime of passion. "Our suspicion is that it was some kind of an argument that went bad," the official said at the time.

The men appear to be the first arrested since a security agreement between Iraq and the United States went into effect this year.

Under the agreement, laboriously negotiated over months in 2008, U.S. contractors, including those working for the American military, are subject to criminal law in Iraq, where the death penalty remains a possible punishment. Contractors working for the State Department and other U.S. agencies retain their immunity. U.S. soldiers remain immune unless they commit "major premeditated felonies" while off duty and off base.

Before the agreement took effect, all contractors were immune from the Iraqi legal process under an order signed by L. Paul Bremer, the head of the Coalition Provisional Authority, in June 2004. As a result, not a single private security contractor was charged with a crime during the first five years of the war, despite dozens of suspicious shootings of Iraqi civilians.

Among those detained for questioning were Donald Feeney Jr., 55, his son Donald Feeney III, 31, and three other people, including two employees of Corporate Training Unlimited, a Fayetteville, N.C., security firm founded by Donald Feeney Jr.

John Feeney, another son of Donald Feeney Jr., said in a phone interview that Kitterman "was a good friend of my father" and that the two knew each other not only from the Green Zone but also from the time when they both served in the military.

Donald Feeney Jr., a former Delta Force operator, founded the firm in 1986, according to the company's Web site. The company, which has been in Iraq since 2003, trains corporate and other officials in how to operate safely in conflict zones. Feeney was also a chief security consultant for such firms as Shell Oil in Bogota, Colombia, according to the company's Web site.

Kitterman is believed to be the first American killed in a crime inside the Green Zone, although other soldiers and civilians have been killed in rocket and mortar attacks since the zone was set up in 2003 after the U.S.-led invasion.

Since Jan. 1, Iraqi forces have assumed nominal control of the Green Zone. They man entry checkpoints, searching vehicles and examining identity papers. Iraqi authorities have also begun removing the blast walls around the Green Zone and opening closed thoroughfares to alleviate frequent traffic snarls along its walls.

Kitterman worked in Iraq for years for several companies, including Houston-based KBR and Kuwait-based Peregrine. He was a former U.S. Navy chief petty officer.

Correspondents Steve Fainaru and Anthony Shadid, staff writer Peter Finn and special correspondent Qais Mizher contributed to this report.