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

The Americans were detained Wednesday. U.S. and Iraqi officials said yesterday that no charges had yet been filed.

James Fennell, a U.S. Embassy spokesman, said yesterday that consular officials had visited the men a day after their arrest to make sure "they're being afforded their rights under Iraqi law."

Maj. Gen. Abdul-Karim Khalaf, a spokesman for the Interior Ministry, 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.

Among those detained for questioning were Donald Feeney Jr., 55, his son Donald Feeney 3d, 31, and three other people, including two employees of Corporate Training Unlimited, a Fayetteville, N.C., security firm founded by Donald Feeney Jr.

There were conflicting accounts about the arrests 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.

Khalaf 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 Green Zone on May 22. He was 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 U.S. 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 as do U.S. soldiers, unless they commit "major premeditated felonies" while off duty and off base.

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 from the time 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 operating in conflict zones.

Kitterman, who founded a construction company in the Green Zone, had worked in Iraq for years for several companies, including Houston-based KBR and Kuwait-based Peregrine. He is a former U.S. Navy chief petty officer.