Beiji, Iraq ? Investigators believe American soldiers spent nearly a week plotting an attack in which they raped an Iraqi woman, then killed her and her family in an insurgent-ridden area south of Baghdad, a U.S. military official said Saturday.

The official, speaking on condition of anonymity because the investigation is ongoing, said the attack appeared “totally premeditated” and that the soldiers apparently “studied” the family for about a week before carrying out the attack.

According to the official, the Sunni Arab family had just moved into a new home in the religiously mixed area about 20 miles south of Baghdad. The Americans entered the home, separated three family members from the woman, then raped her and set fire to her body, the official said. The three others were also slain. A senior Army official who also requested anonymity because the investigation is ongoing said one of the victims was a child.

U.S. officials said they knew of the deaths but thought the victims died due to sectarian violence. A local police official, Capt. Ihsan Abdul-Rahman, said Iraqi officials received a report March 13 alleging that American soldiers had killed the family in the Khasir Abyad district about 6 miles north of Mahmoudiya.

He said he did not relay that report to American forces.

The satellite channel Al-Jazeera gave wide coverage to the alleged rape-slaying, which threatens to stoke public anger in the wake of a series of other cases of U.S. troops allegedly killing and abusing Iraqi civilians.

An Iraqi human rights activist in Amman, Jordan, pointed to other abuse allegations, in the western Iraqi town of Haditha, and called for international intervention.

“What happened in Mahmoudiya and Haditha are extreme violations of human rights. We call on the international community to intervene immediately,” Mohammed al-Shekhli, head of the head of the Transitional Justice Studies Center, said in an interview with the pan-Arab satellite station.

However, Iraqi media has so far paid little attention to the allegations. There was no comment from the government, which has been focused on restoring security since it took office in May.

One of the officials familiar with details of the investigation told The Associated Press that a flammable liquid was used to burn the woman’s body in a cover-up attempt. It was unclear if it was gasoline or lighter fluid.

If convicted of premeditated murder, the soldiers could receive a death sentence under U.S. military law.

The U.S. official said at least four soldiers were being investigated. Two other U.S. officials said Friday that five were under investigation but one already had been discharged for unspecified charges unrelated to the killings and was believed to be in the United States.

The U.S. command has said only that Maj. Gen. James D. Thurman, commander of U.S. forces in the Baghdad area, had ordered a criminal investigation into the alleged slaying of a family of four.

Those troops under investigation are from the same platoon as two soldiers kidnapped and killed south of Baghdad this month, another official said Friday. Their mutilated bodies were found June 19, three days after they were abducted by insurgents near Youssifiyah, southwest of Baghdad.