Three soldiers who were expected to testify in the civilian trial of a former soldier accused of raping and killing a 14-year-old girl in Iraq are likely to refuse, federal prosecutors said.

Prosecutors asked a federal judge to force the testimony of the soldiers at the trial of former 101st Airborne Pfc. Steven Dale Green. Acting U.S. Attorney Candace Hill said the soldiers — James Barker, Paul Cortez and Anthony Yribe — may invoke their right against self-incrimination if called to testify at Green's trial, which is scheduled to start Monday in Paducah.

The three previously testified about the killing in military court.

The 23-year-old Green, of Midland, Texas, has pleaded not guilty. He faces a possible death sentence on charges that he raped and shot Abeer Qassim al-Janabi, then shot and killed her family in 2006 in Mahmoudiya, Iraq.

Green is being prosecuted in federal court because he was discharged from the military before being charged.

Barker and Cortez, who were assigned with Green to the 1st Battalion, 502nd Infantry Regiment of the Fort Campbell, Ky.-based 101st Airborne Division, each pleaded guilty in military court to their roles in attack in Iraq.

Barker was sentenced to 90 years in prison, and Cortez, 100 years.

Hill said in the motions that the testimony of each soldier "may be necessary to the public interest."

Barker told a military court that Green approached him with a plan to attack the family as the soldiers drank whiskey bought from Iraqi soldiers.

Barker described changing clothes, then climbing through backyards as the five soldiers left the checkpoint they had been staffing to carry out the attack.

Barker and Cortez also described how they raped the teenager with Green before Green killed the girl, her younger sister and parents.

Later, Barker testified that he had allowed investigators to draft sworn statements for him that implicated another soldier and that several portions of the document were untrue.

Cortez, of Barstow, Calif., pleaded guilty to four murders, rape and conspiracy to rape. Cortez, in his plea agreement, said while raped the girl, Green shot and killed the girl's parents and younger sister.

Cortez testified that he then acted as a lookout while Green raped the girl, and Green shot her. Cortez testified that he helped burn the girl's body and the home, then burned his clothes.

Yribe was accused of failing to report the crime, but charges against him were not referred to court-martial. He admitted during a July 2007 court-martial of another soldier to making false statements to military investigators and battalion commanders following the assault, and failing to report what Green had told him.

Capt. Howard Clayton, an attorney for Cortez, could not immediately be reached for comment. Attorneys for Barker and Yribe could not immediately be located Friday. A message left for Darren Wolff, one of Green's attorneys, was not immediately returned Friday.