The U.S. military charged Army Staff Sgt. Robert Bales on Friday with murdering 17 Afghans during a village massacre this month but did not shed light on a possible motive for the worst U.S. atrocity of the decade-long war.

Bales, 38, a member of an infantry unit and the married father of two young children, was formally presented with the charges at Fort Leavenworth, Kan., where he is being held in a maximum-security military prison.

In a statement from Kabul, the U.S. military said Bales was also charged with assaulting and attempting to murder six other Afghan civilians during a rampage in the early morning hours of March 11. Most of the dead were women and children, and some of the bodies were burned, U.S. and Afghan officials have said.

Col. Gary Kolb, a U.S. military spokesman in Kabul, said Bales is alleged to have walked off base armed with a 9mm pistol and an M-4 rifle with a grenade launcher.

The U.S. military released charging documents in the case but redacted the names of victims in the shootings. Military officials have not provided a timeline of the events surrounding the killings or offered a motive for the alleged crimes.

The massacre, in the Panjwai district of Kandahar province, has roiled relations between the United States and Afghanistan at a time when American commanders are seeking to stabilize the country in preparation for an eventual U.S. exit. President Obama has promised to hold accountable “anyone responsible” for the killings.

In its statement, the military said Bales acted with pre-meditation and that he could be subject to the death penalty if the case proceeds to court-martial and he is convicted.

Bales’s civilian attorney has said his client does not remember much about what happened on March 11, when the military alleges he committed the massacre and returned to the base on his own to surrender.

“This is going to be a very difficult case for the government to prove, in my opinion,” the lawyer, John Henry Browne, said on “CBS This Morning” on Friday. “There is no crime scene. There is no, you know, there’s no ‘CSI’ stuff. There’s no DNA. There’s no fingerprints. It’s just going to be interesting to see how the government’s going to prove this.”

Bales had deployed three times to Iraq. He arrived in Afghanistan for the first time in December with other members of the 3rd Stryker Combat Brigade, 2nd Infantry Division, a unit from Joint Base Lewis-McChord in Washington state.

Bales called his wife, Kari, from Afghanistan after U.S. forces took him into custody March 11, and told her “something terrible happened,” a Seattle attorney for Kari Bales said Friday.

But the soldier uttered that phrase “in the context that he was custody in jail and not in the sense of ‘I did something terrible,’ ” said Seattle attorney Lance S. Rosen, who is representing Kari Bales in dealings with the media.

The lawyer said Bales was told he could call his wife briefly by military officials detaining him. “I know very little about the call and what was said,” said Rosen, who is not on the defense team for Robert Bales.

Authorities had previously said 16 Afghans were killed and several others critically wounded. They did not offer a public explanation for why Bales was charged with 17 counts of murder.

But a U.S. military official, speaking on the condition of anonymity because of the sensitivity of the case, said forensic investigators subsequently determined that 17 bodies were at the scene. The dead included 10 females and seven males. The ages of the dead were not disclosed in the charging documents, but those wounded in the massacre included eight children.

The decision to formally charge Bales did nothing to dampen the anger of Mohammed Wazir, who lost 11 family members — including his mother, wife, four daughters and two sons — in the rampage.

Wazir, 35, said he did not believe that a military trial in the United States could ever bring justice.

“This is not acceptable for us,” Wazir said in an interview Friday from the Afghan town of Spin Boldak. “We want him to be tried in Afghanistan, in our presence.”

A farmer and trader, Wazir lived in a mud home in Najeeban, one of the two tiny villages in the Panjwai district of Kandahar province that Bales allegedly targeted. Also shot and killed in Wazir’s home were his brother, his brother’s wife and their child, according to Wazir and other villagers.

At the time of the attack, Wazir was in Spin Boldak, about 85 miles south, with his 4-year-old son, Habib Shah. Habib is now his only surviving child.

Four others apparently were killed in Alokozo, a neighboring village of 20 homes. Samisami-Ullah, a 30-year-old farmer, identified those victims as his mother, uncle and two cousins. Three others in his family were wounded, he said, along with three from his neighbors’ families. Five of the six wounded were transported to a U.S. military hospital, where three victims remain.

To date, the U.S. military has not contacted any witnesses or those who lost relatives, said Wazir, provincial officials and others who have talked to the massacre victims’ families.

“None of them have come to investigate, or to talk to us, or seen the village,” Wazir said angrily. “We want justice.”

Leiby reported from Kabul. Correspondent Ernesto Londoño in Kabul and staff writers Mary Pat Flaherty and Julie Tate in Washington contributed to this report.