U.S. soldiers accused of raping and murdering a 14-year-old Iraqi girl drank alcohol and hit golf balls before the attack, and one of them grilled chicken wings afterward, an investigator told a U.S. military hearing Monday, citing a soldier's sworn statement.

Criminal investigator Benjamin Bierce told the hearing that he interviewed one of the accused, Spc. James P. Barker, on June 30, and recorded graphic and brutal sexual details of the alleged March 12 assault.

Bierce was testifying on the second day of the hearing to determine whether five U.S. soldiers must stand trial in the rape-slaying of Abeer Qassim al-Janabi and the killing of her parents and 5-year-old sister in the town of Mahmoudiya, one of the most violent areas in Iraq.

CountryWatch: Iraq

The rape and murders are among the worst in a series of cases of alleged misconduct by American service members that have tarnished the American military. U.S. soldiers' conduct has come under the spotlight over a string of similar cases.

Barker's sworn and signed statement was submitted in evidence during the hearing. Parts were revealed during Bierce's testimony.

Barker is accused along with Sgt. Paul E. Cortez, Pfc. Jesse V. Spielman, Pfc. Bryan L. Howard of rape and murder. Another soldier, Sgt. Anthony W. Yribe, is accused of failing to report the attack but is not alleged to have been a direct participant.

Former Pfc. Steven D. Green was discharged from the Army for a "personality disorder" after the incident and was arrested in North Carolina in June on rape and murder charges. He has pleaded not guilty in federal court and is being held without bond.

At Monday's hearing, Pfc. Justin Watt, testified that Howard told him before the incident that Green, Cortez and Barker had planned to rape a girl, and Howard was to be the lookout.

"There's nothing I've read that says what to do if your buddies have raped and murdered a family," Watt said.

According to Barker's sworn statement cited by Bierce, Green not only raped the girl but also shot her and her family members after telling his comrades repeatedly that he wanted to kill some Iraqis.

Bierce testified that on the day of the attack, Barker, Cortez, Spielman and Green had been playing cards and drinking Iraqi whiskey mixed with an energy drink. Afterward, they practiced hitting golf balls, Bierce quoted Barker as saying in his statement.

Bierce said Barker's statement made it clear that Green was very persistent about killing some Iraqis and kept bringing up the idea. At some point they decided to go to the house of the girl, whom they had seen passing by their checkpoint earlier.

According to Bierce, Barker told him that when they arrived at the house, the father and the girl were outside the house. Spielman grabbed the girl while Green seized her father and took them into the house with, Bierce said, quoting Barker. Cortez and Barker also went in.

Green took the father, mother and the younger sister into the bedroom and closed the door, while the girl remained in the living room with the others.

Barker wrote that Cortez pushed the girl to the floor, lifted her dress and tore off her underwear while she struggled, Bierce said. Cortez apparently raped her or appeared to rape her, according to Barker's statement, Bierce said.

Barker then tried to rape the girl, Bierce said. Suddenly, the group heard gunshots. Green came out of the bedroom holding an AK-47 rifle and declared: '"They're all dead. I just killed them,"' Bierce said, quoting Barker's statement.

Green put the gun down, then raped the girl while Cortez held her down; Barker claims Green picked up the AK-47 and shot the girl once, paused, then shot her several more times, Bierce said.

Barker confirms he got a kerosene lamp and poured the fuel on the girl, Bierce said. The body was set on fire, but Barker does not say who did it. Barker's statement also does not say if Howard or Spielman participated in the rape.

Barker's statement says he grilled chicken wings once they got back to their checkpoint, Bierce testified. A few hours later, Barker wrote, Iraqi army soldiers came to report they had found a family murdered.

Since the case became public last month, U.S. officials have said they were concerned it could strain relations with Iraq's new government if Iraqis perceive that the soldiers receive lenient treatment.

They have offered assurances that the case will be pursued vigorously and that the soldiers will be punished if convicted.

The case has already increased demands for changes in an agreement that exempts U.S. soldiers from prosecution in Iraqi courts. And Prime Minister Nouri al-Maliki has demanded an independent investigation into the case.