The house in Mahmudiya where the rape and killings took place

Sgt Paul Cortez will no longer face the death penalty and has agreed to co-operate in the trials of three other men, his lawyer said.

A fifth man, Spc James Barker, pleaded guilty in November and was sentenced to life in prison.

The case is one of several in which US troops are accused of killing Iraqis.

Prosecutors say the five plotted the attack on the girl and her family.

Several cases

The soldiers are accused of breaking into the girl's home, raping and murdering her, and then killing her parents and her six-year-old sister.

"Sgt Cortez is going to go in and accept the responsibility for his part in what occurred," his lawyer William Cassara said.

Sgt Cortez is going to go in and accept the responsibility for his part in what occurred

Lawyer William Cassara

"Our version of events is that he knew what was going to take place and participated as an observer."

He is expected to officially enter his plea on 20 February in a hearing at Fort Campbell, Kentucky, home of the 101st Airborne Division which all five soldiers belonged to.

Two other soldiers - Pvt Jesse Spielman and Pvt Bryan Howard - are facing court-martial proceedings on charges related to the attack.

Former soldier Steven Green has been charged in a civilian court in Kentucky with murder and sexual assault. He has denied the charges.

The Mahmudiya case is one of several involving accusations of US attacks or abuses against Iraqi civilians.

A marine, Cpl Trent Thomas, has pleaded guilty to the murder of an Iraqi man in the town of Hamdaniya.

Cpl Thomas is one of seven marines and a navy medic charged in the April, 2006 kidnapping and killing of 52-year-old Hashim Awad.

Petty Officer Melson J Bacos was sentenced to 10 years in prison last October but is expected to spend one year in jail after agreeing to give evidence against the seven marines charged with the murder.