An army officer and seven soldiers are being detained in connection with the killing of 22 people in rural southern Mexico, an encounter that the military initially reported as a shootout but that a witness later described as a massacre.
The Mexican Defense Department said in a statement late Thursday that the eight were involved in the June 30 incident in San Pedro Limon, but did not specify how. They were being held at a prison in Mexico City on charges of crimes against military discipline, disobedience and dereliction of duty.
The statement said the military charges are being pursued "independently of the investigations that civil authorities are carrying out under their jurisdiction."
The federal Attorney General's Office, which is conducting a criminal probe of the killings, had no immediate comment.
Raul Plascencia, president of Mexico's National Human Rights Commission, reserved comment, saying the Defense Department statement was not clear on the soldiers' connection to the killings. Plascencia's commission is also investigating the case.
Recent reforms require that alleged military offences against civilians be tried in civilian courts, but doesn't bar the military justice system from pursuing its own charges.
Shortly after the confrontation, the army reported that 22 suspected criminals had been killed in a firefight with troops. Only one soldier was wounded. The official version came into question when The Associated Press visited the scene days later and found no sign of a prolonged battle.
At least five spots inside the warehouse where the bloodshed occurred showed the same pattern: One or two closely placed bullet pocks, surrounded by a mass of spattered blood, giving the appearance that some of those killed had been standing against a wall and shot at about chest level.
Officials insisted firefight took place
Last week, a woman who says she witnessed the events told the AP that only one person died in the initial confrontation and the rest were shot after surrendering. The witness said the dead included her 15-year-old daughter, who had been wounded in the leg and was lying on the ground when she was killed.
Until recently, officials have stood by the initial account of a fierce firefight.
In July, the state of Mexico prosecutors' office released a statement saying there was "no evidence at all of possible executions." The office said it found ballistic evidence of "crossfire with a proportionate interchange of gunshots."
The state government refused to release autopsy reports that the AP requested under Mexico's freedom of information law, declaring them state secrets to be guarded for nine years.
The federal Attorney General's Office last week said that so far it had not found evidence corroborating the witness' account.
But this week, President Enrique Pena Nieto said in New York that the Attorney General's Office was diving into the investigation and would answer all questions. Army leaders also spoke of cooperating with the investigation and punishing any violations of human rights.
The U.S. State Department and international rights groups have called for thorough investigations. Human Rights Watch said the incident could prove to be one of the "most serious massacres in Mexico."