Washington (CNN) -- Afghanistan's foreign minister called for a "swift and transparent investigation" into the killings of 16 men, women and children Wednesday as the U.S. soldier arrested in the massacre awaited charges.
On Wednesday, Staff Sgt. Robert Bales' attorney John Henry Browne said he's now hearing that homicide and other charges against his client might be filed Friday. And after a meeting in Washington with Secretary of State Hillary Clinton, Afghan Foreign Minister Zalmai Rassoul said his government was looking forward to seeing justice done.
"We are awaiting the swift and transparent investigation of this case and the punishment of anyone involved," Rassoul said. "That will greatly reinforce the Afghan people's confidence in the existent strong friendship and partnership with the United States."
Bales was flown out of Afghanistan last week and is being held at Fort Leavenworth, Kansas. Afghans are insisting that the suspect be returned to Afghanistan to face trial, even as villagers and lawmakers question the U.S. military's account of what happened. But a military official said in Afghanistan on Sunday that Bales will be tried in the United States.
"We are doing some coordination to find out what the final venue will be, but the proceedings will take place somewhere in the United States," said the official, identified only as a "U.S. Forces Afghanistan Legal Expert."
The rampage has strained already tense U.S.-Afghan relations and intensified a debate about whether to pull American troops ahead of their planned 2014 withdrawal. Afghan President Hamid Karzai demanded that troops withdraw from villages and return to their bases. He said relations between the two countries were "at the end of their rope."
After her meeting with Rassoul, Clinton said the United States "deeply regretted" the killings and an earlier incident in which U.S. troops accidentally burned copies of the Quran, sparking deadly riots and fatal attacks on U.S. troops.
"This has been very personally painful to me and to the president," she said. "It does not represent who the United States is, who the American people are, and we appreciate the understanding and response of the Afghan government and the Afghan people."
U.S. officials have alleged that Bales carried out the killings alone in two neighboring villages in the Panjwai district of Kandahar province, in southern Afghanistan. And Hajji Agha Lalai Desdageeri, a member of the Afghan parliament from Kandahar province, said two people wounded in the massacre backed that up in interviews in a NATO hospital.
Desdageeri said U.S. commanders have offered compensation to the survivors, "but so far, none has been received and no amount offered."
"On the day of the incident, Gen. John Allen called me and was very upset about the incident," he said. He said Allen told him, "We will punish the perpetrator. It was only one person. We will help the victims' families."
Allen is the chief of U.S. and NATO forces in Afghanistan.
Browne said his client, who had served three tours of duty in Iraq before being sent to Afghanistan, may have been suffering post-traumatic stress disorder, but he added that the government may have a hard time demonstrating that the Army sergeant was behind the killings.
"I don't know if the government is going to prove much," Browne said Tuesday. "There's no forensic evidence. There's no confessions."
Desdageeri said no post-mortem examinations of the victims had been performed because village residents "said, 'No, this is not acceptable.' "
The military will conduct a separate investigation into the circumstances surrounding Bales' assignment to the combat outpost in southern Afghanistan, Allen said Tuesday.
The administrative review, which will take place separately from the criminal investigation, will be conducted by U.S. Forces Afghanistan, Allen told the House Armed Services Committee.
The investigation will consider how Bales was assigned and why he was assigned to the combat outpost, Allen said. "It will look at the command relationships associated with his involvement in that combat outpost," Allen said.
A defense official said the military had not started the investigation. "It is in preparation to start soon," said the official, who was not authorized to speak on the record and asked not to be identified. "That is by design not to conflict with the criminal investigation."
The inquiry will examine other administrative, training and command channels "to see if anything can be attributed to the incident," the official said.
The official said the investigation will go beyond Bales' time in Afghanistan and will look at deployment decisions and training he received prior to arriving in that country.
Accounts from the military, Bales' family, friends and neighbors paint a portrait of a man who bore scars from wounds he received during three previous combat tours to Iraq but remained committed to serving his country and deployed to Afghanistan in January.
CNN's Miguel Marquez and journalist Fazal Ahad contributed to this report.