MEXICO CITY (AP) — A human rights group said Thursday that military documents show high-ranking officers had given Mexican soldiers standing orders to kill criminals ahead of an army mass slaying of suspected cartel members after they surrendered.

The documents, shared with The Associated Press by the Miguel Agustin Pro human rights center, appear to be the first evidence that soldiers involved in the alleged execution killing of at least 12 civilians on June 30, 2014, could argue they were following orders.

"Soldiers should operate on a mass scale at night and reduce daytime activities, with the aim of killing criminals at night," read standing orders signed June 11 by Lt. Col. Sandro Diaz Rodriguez, on behalf of the command of the 102 Infantry Battalion.

At the same time, the orders told soldiers that "operations should be carried out with strict respect for human rights."

The documents also indicate high-ranking military officials knew immediately that something had gone wrong in the incident a year ago at a rural warehouse, during which a total of 22 suspected gang members were killed, according to a report by the human rights group.

The documents show the army opened a criminal investigation the same day of the incident, yet issued a news release saying all 22 dead had been killed during a fierce gunbattle that began when the suspects fired on soldiers.

The Defense Department did not immediately respond to a request for comment Thursday.

But in an interview Monday with the newspaper El Universal, the defense secretary, Gen. Salvador Cienfuegos, cast doubt on the alleged human rights violations.

"People and groups who perhaps don't like what the army is doing have already convicted the soldiers," he said. "They talk about people being forced into submission. I don't understand how they could have been forced into submission when there were eight soldiers who didn't know how many people were inside the warehouse."

A National Human Rights Commission investigation found that between 12 and 15 of the victims were killed unarmed or after surrendering. Three women who survived the attack later came forward to say that agents of the Mexico State prosecutor's office had tortured them to support the army's version that soldiers had killed in self-defense.

One of the survivors, whose daughter was among those killed, spoke publicly for the first time about the shootings Thursday. "I want justice to be done, justice for what they did to my daughter. God will not forgive them," said Clara Gomez.

Her daughter is not considered by federal prosecutors to be among those killed after surrendering, but Gomez, a witness, said her daughter was still alive and wounded after the shootout, then she later found her shot dead.

The Defense Department has said the killings in the municipality of Tlatlaya west of Mexico City were the work of seven soldiers charged in the case and it has not implicated any ranking officers.

Questions about the killings were first brought to light by an Associated Press report that pointed out contradictions in the army's account. AP journalists who visited the scene three days after the shooting found little evidence of a long gun battle. Instead, the walls showed a repeated pattern of one or two closely placed bullet holes surrounded by spattered blood, giving the appearance that some of those killed had been standing against a wall and shot at about chest level.

"If the order was to kill, then that is a violation of the (army's) manual on use of force ... because lethal force can only be used in certain circumstances," said security analyst Alejandro Hope, a former official in Mexico's domestic intelligence service. "This may open the discussion of how high up the investigation of the Tlatlaya case should reach ... whether the investigation should include the whole chain of command."

The army has been allowed to participate in law enforcement and anti-drug operations only under a role of "assisting" police and prosecutors.

The Armed Forces Manual on the Use of Force states that soldiers "can only use their firearms in legitimate defense of themselves or of other people, in cases of danger of imminent death or serious injury, or to prevent the commission of a crime that involves a threat to life, and only in the case where other less extreme measures are insufficient to achieve those objectives."

In a transcript of a statement to prosecutors, one of the accused soldiers repeats the Spanish word "abatir," or "kill," when asked what he did on the morning of June 30. That is the word contained in the standing orders the unit received when deployed to the area.

In November, three of the soldiers on the patrol were charged with aggravated homicide and four others, including a lieutenant, were charged with "actions improper to the public service" for failing to report the killings.

There have been no trials or verdicts in the case.

Late Wednesday, the Mexico State prosecutor's office formally accused seven state police officers of torturing the three women. Four of the police officers have been detained and a judge is expected to issue an arrest warrant for the other three, according to a statement from the office.