The announcement followed a pretrial hearing last month for Staff Sgt. Robert Bales, 39, who faces premeditated murder and other charges in the attack on two villages in southern Afghanistan.

The slayings drew such angry protests that the U.S. temporarily halted combat operations in Afghanistan, and it was three weeks before American investigators could reach the crime scenes.

Prosecutors said Bales left his remote southern Afghanistan base early on March 11, attacked one village and returned to the base, then slipped away again to attack another nearby compound. Of the 16 people killed, nine were children.

No date has been set for Bales’ court martial, which will be held at Joint Base Lewis-McChord south of Seattle.

His civilian lawyer, John Henry Browne, told The Associated Press he met with Army officials last week to argue his client shouldn’t face the possibility of the death penalty, given that Bales was serving his fourth deployment in a war zone when the killings occurred.

“The Army is not taking responsibility for Sgt. Bales and other soldiers that the Army knowingly sends into combat situations with diagnosed PTSD, concussive head injuries and other injuries,” Browne said. “The Army is trying to take the focus off the failure of its decisions, and the failure of the war itself, and making Sgt. Bales out to be a rogue soldier.”

Bales’ wife, Kari Bales, said in a statement Wednesday that she and their children have been enjoying their weekend visits with Bales at Joint Base Lewis-McChord, and she hopes he receives an impartial trial.

“I no longer know if a fair trial for Bob is possible, but it very much is my hope, and I will have faith,” she said.

Bales’ defense team has said the government’s case is incomplete, and outside experts have said a key issue going forward will be to determine if Bales suffered from post-traumatic stress disorder. Bales grew up in the Cincinnati suburb of Norwood, Ohio, and served tours of duty in Iraq and Afghanistan.

During last month’s preliminary hearing, prosecutors built a strong eyewitness case against the veteran soldier, with troops recounting how they saw Bales return to the base alone, covered in blood.

Afghan witnesses questioned via a video link from a forward operating base near Kandahar City described the horror of that night. A teenage boy recalled how the gunman kept firing as children scrambled, yelling: “We are children! We are children!” A young girl in a bright headscarf recalled hiding behind her father as he was shot to death.

An Army criminal investigations command special agent testified earlier that Bales tested positive for steroids three days after the killings, and other soldiers testified that Bales had been drinking the evening of the massacre.

Prosecutors, in asking for a court-martial trial, have pointed to statements Bales made after he was apprehended, saying his comments demonstrated a “clear memory of what he had done, and consciousness of wrongdoing.”

Several soldiers testified at a hearing that Bales returned to the base alone just before dawn, covered in blood, and that he made incriminating statements such as, “I thought I was doing the right thing.”

The U.S. military has not executed anyone since 1961. There are five men currently facing military death sentences, all for murders committed stateside, according to the Death Penalty Information Center. Nidal Hasan, charged in the 2009 rampage that killed 13 and wounded more than two dozen others at Fort Hood in Texas, also could face the death penalty if convicted; no date has been set for his court martial.

For Bales to face execution, the court martial jury must unanimously find him guilty of premeditated murder. They also must determine that at least one aggravating factor applies, such as multiple or child victims, and that the aggravating factor substantially outweighs any extenuating or mitigating circumstances.