BEIJI, Iraq - A group of American soldiers in an insurgent-riddled town allegedly noticed a young Iraqi woman when on patrol and later returned to rape her, according to U.S. officials Friday. In an apparent cover-up attempt, she and three members of her family then were killed and her body was set on fire.

Five U.S. troops are being investigated, a U.S. military official told The Associated Press. It was the sixth known inquiry into alleged slayings of Iraqi civilians by U.S. troops.

The suspects in the killing, which took place in March, were from the same platoon as two soldiers kidnapped and killed south of Baghdad this month, said the official, who is close to the investigation and spoke on condition of anonymity because of the sensitivity of the case.

One soldier was arrested after admitting his role in the alleged attack on the family, the U.S. official said. The official said the rape and killings appear to have been a "crime of opportunity," noting that the soldiers had not been attacked by insurgents but had noticed the woman on previous patrols.

One of the family members they allegedly killed was a child, said a senior Army official who also requested anonymity because the investigation is ongoing. Some of the suspects allegedly burned the woman's body to cover up the attack, the U.S. official said.

In Baghdad, the U.S. military issued a sparse statement, saying only that Maj. Gen. James D. Thurman, commander of the 4th Infantry Division, ordered a criminal investigation into the alleged slaying of a family of four in Mahmoudiya, 20 miles south of Baghdad.

However, the U.S. official said the soldiers were assigned to the 502nd Infantry Regiment. The official told the AP that the suspects were from the same platoon as two slain soldiers whose mutilated bodies were found June 19, three days after they were abducted by insurgents near Youssifiyah southwest of Baghdad.

The military has said one and possibly both of the slain soldiers were tortured and beheaded. The official said the mutilation of the slain soldiers stirred feelings of guilt and led at least one member of the platoon to reveal the rape-slaying on June 22.

According to the senior Army official, the alleged incident was first revealed by a soldier during a routine counseling-type session. The official said that soldier did not witness the incident but heard about it.

A second soldier, who also was not involved, said he overhead soldiers conspiring to commit the crimes and then later saw bloodstains on their clothes, the official said.

Before the soldier disclosed the alleged assault, senior officers had been aware of the family's death but believed it was a result of sectarian violence, the official said.

One of the five suspects has already been discharged for unspecified charges unrelated to the killings and is believed to be in the United States, two U.S. officials said on condition of anonymity because the investigation is ongoing. The others have had their weapons taken away and are confined to a U.S. base near Mahmoudiya.

The allegations of rape could generate a particularly strong backlash in Iraq, a conservative, strongly religious society in which many women will not even shake hands with men who are not close relatives.

The case is among the most serious against U.S. soldiers allegedly involved in the deaths of Iraqi civilians. At least 14 U.S. troops have been convicted.

Last week, seven Marines and one Navy medic were charged with premeditated murder in the shooting death of an Iraqi man near Fallujah west of Baghdad.

U.S. officials are also investigating allegations that U.S. Marines killed two dozen unarmed Iraqi civilians Nov. 19 in the western town of Haditha in a revenge attack after a fellow Marine died in a roadside bombing.

Other cases involve the deaths of three male detainees in Salahuddin province in May, the shooting death of unarmed Iraqi man near Ramadi in February, and the death of an Iraqi soldier after an interrogation in 2003 at a detention camp in Qaim.

The allegations have aroused public anger against the U.S. military presence at a time when the new Iraqi government and U.S. authorities are trying to reach out to disaffected Sunni Arabs to quell the insurgency and calm sectarian tensions.

On Saturday, Prime Minister Nouri al-Maliki leaves for a whirlwind trip to Saudi Arabia, Kuwait and the United Arab Emirates to seek support for his national reconciliation initiative, which includes an amnesty for the mostly Sunni insurgents.

Al-Maliki is also expected to brief the Sunni leadership of those three countries on his efforts to deal with the divisions between Shiites and Sunnis. Iraq's neighbors in the Persian Gulf fear sectarian tensions will spill over into their countries, which are dominated by Sunnis but have large Shiite minorities.

On Friday, radical Shiite cleric Muqtada al-Sadr rejected al-Maliki's initiative because it does not include a timetable for the withdrawal of U.S.-led foreign troops.

"We demand the occupation forces to leave the country, or at least a timetable should be set for their withdrawal," al-Sadr said during a sermon.

Despite al-Maliki's efforts, there has been no letup in Iraq's violence. The U.S. military reported four more American service members have died, including a Marine killed Friday in fighting west of Baghdad. Three Army soldiers died in combat the day before, the military said.

- AP correspondent Ryan Lenz is embedded with the 101st Airborne Division in Beiji, Iraq. He was previously embedded with the 502nd Infantry Regiment in Mahmoudiya. AP correspondent Lolita C. Baldor in Washington contributed to this report.

AT A GLANCE

A look at criminal cases against U.S. soldiers stemming from the deaths of Iraqis since the war began in 2003: - PENDING CASES:

-Pfc. Corey R. Clagett, Spc. Juston R. Graber, Staff Sgt. Raymond L. Girouard and Spc. William B. Hunsaker charged with premeditated murder of three male detainees in Salahuddin province in May. Clagett, Girouard and Hunsaker also charged with obstructing justice for allegedly threatening to kill another soldier who was a witness in the case.

-Hospitalman Third Class Melson J. Bacos; Sgt. Lawrence G. Hutchins III; Lance Cpl. Tyler A. Jackson; Pfc. John J. Jodka; Cpl. Marshall L. Magincalda; Lance Cpl. Robert B. Pennington; Lance Cpl. Jerry E. Shumate Jr.; and Marine Cpl. Trent D. Thomas charged with premeditated murder in April shooting death of Iraqi man in Hamdania. All eight also charged with kidnapping, larceny, conspiracy, assault and housebreaking.

-Five U.S. Army soldiers from 502nd Infantry Regiment being investigated for allegedly raping a young woman in March, then killing her and three members of her family in Mahmoudiyah, south of Baghdad, a U.S. military official tells The Associated Press.

-National Guard Sgt. Milton Ortiz Jr. and Spc. Nathan B. Lynn charged in shooting death of unarmed Iraqi man near Ramadi in February. Both also charged with obstructing justice. Lynn charged with voluntary manslaughter. Ortiz also faces charges of assault and communicating a threat in separate incident involving another Iraqi man.

-Capt. James Kimber, Capt. Lucas M. McConnell, Staff Sgt. Frank D. Wuterich and an unidentified Marine under investigation for killings of two dozen unarmed Iraqi civilians in western town of Haditha on Nov. 19, 2005 in revenge attack after one of their own died in a roadside bombing. Probe focusing on allegations that the Marines stormed into nearby homes and shot occupants as well as others outside, according to U.S. lawmakers briefed by military officials. Separately, the military also investigating if there was a coverup. Iraqi government said it will also investigate.

-Chief Warrant Officer Jefferson L. Williams, Sgt. 1st Class William Sommer and Spc. Jerry Loper charged with murder and dereliction of duty, along with Chief Warrant Officer Lewis Welshofer, an incident in resulting in death of Iraqi Maj. Gen. Abed Hamed Mowhoush after an interrogation in 2003 at a detention camp in al Qaim. Army dropped murder charges against Williams and Loper in exchange for testimony against Welshofer. Murder charge against Sommer also dropped. Both Sommer and Williams face possible administrative discipline.

CONVICTIONS:

-Staff Sgt. Cardenas J. Alban convicted of killing severely wounded 16-year-old Iraqi during fighting in Baghdad's Sadr City neighborhood. Sentenced to one year's confinement, demoted to private and given bad-conduct discharge.

-Staff Sgt. Johnny Horne Jr. pleaded guilty to unpremeditated murder in same case as Alban. Sentenced to three years in prison, had rank reduced to private, forfeited wages and given dishonorable discharge. Horne's prison sentence later reduced to one year.

-Cpl. Dustin Berg of Indiana National Guard convicted and sentenced to 18 months in military prison for shooting death of Iraqi police officer.

-Spc. Rami Dajani convicted of making a false statement following fatal shooting of Iraqi translator. Sentenced to 18 months' confinement and given a reduction in rank and bad conduct discharge.

-Spc. Charley L. Hooser convicted of involuntary manslaughter in same case involving Dajani. Hooser sentenced to three years in prison and given a reduction in rank and bad conduct discharge. Also convicted of making a false statement to investigators.

-Capt. Rogelio "Roger" Maynulet convicted of assault with intent to commit voluntary manslaughter in shooting death of wounded Iraqi. Received no prison time but was dismissed from armed forces.

-Pvt. Federico Daniel Merida of North Carolina National Guard pleaded guilty to killing 17-year-old Iraqi soldier after the two had consensual sex. Sentenced to 25 years in prison, given a reduction in rank and was dishonorably discharged.

-Marine Maj. Clarke Paulus convicted of dereliction of duty and maltreatment in case stemming from death of Iraqi prisoner who was dragged out of holding cell by the neck, stripped naked and left outside for seven hours in June 2003. Paulus, who commanded the Marine detention facility Camp Whitehorse in southern Iraq, was dismissed from the service but received no prison time.

-Sgt. 1st Class Tracy Perkins acquitted of involuntary manslaughter in alleged drowning of Iraqi man but convicted of assault for forcing the man and his cousin into Tigris River. Sentenced to six months in prison.

-1st Lt. Jack Saville pleaded guilty to assault and other crimes in same incident as Perkins. Sentenced to 45 days in military prison.

-Pfc. Edward Richmond convicted of voluntary manslaughter for shooting Iraqi in back of head. Received three years in prison.

-Sgt. Michael P. Williams convicted in court-martial of one count of premeditated murder and one count of unpremeditated murder in deaths of unarmed civilians during operations near Sadr City. Sentenced to life in prison and given a reduction in rank. Sentence later reduced to 25 years.

-Spc. Brent May convicted in court-martial of one count of unpremeditated murder in same incident as Michael Williams. Sentenced to five years in prison.

-Welshofer, of 3rd Armored Cavalry Regiment, initially charged with murder, assault and willful dereliction of duty but found guilty of negligent homicide and negligent dereliction of duty in death of Mowhoush. Military jury ordered a reprimand and forfeiture of $6,000 of his salary and restricted him to his home, office and church for two months.

CLEARED/ACQUITTED:

-U.S. troops cleared of intentionally killing civilians in March 15 raid in village of Ishaqi. Military acknowledged "possibly up to nine collateral deaths" in addition to four announced at time of the raid. Iraqis said there were 11 dead.

-Marine 2nd Lt. Ilario Pantano cleared of murder charges in shooting deaths of two Iraqi civilians.

-Staff Sgt. Shane Werst acquitted by jury of premeditated murder for shooting death of unarmed Iraqi.

-Information compiled by The Associated Press News and Information Research Center.