At least 20 Mexico state officials are under investigation in the cover-up of threats and torture of women who were witnesses to the alleged killing of prisoners by soldiers last year, state authorities said Wednesday.

State attorney for Mexico state, Alejandro Gomez, said the officials under investigation include prosecutors, forensic investigators and state police.

On June 30, soldiers killed 22 alleged gang members at a warehouse in Tlatlaya. The army first said they died during a shootout, but it was discovered that some were executed.

Federal investigators have said eight people were killed after surrendering to the soldiers, but the National Human Rights Commission put the number between 12 and 15.

The commission also said the state attorney's office tried to cover up the torture and sexual threats endured by at least two of the three women who survived.

"None have been removed from duty yet because there is a presumption of innocence," Gomez said at a news conference. He said it was not clear when a determination would be made about the officials' involvement.

In a recent interview with The Associated Press, one of the witnesses described the torture she suffered. She said that when she refused to sign a false statement that all 22 had died in a shootout with soldiers, state officials kicked her in the ribs, shoved her head into a toilet and hit her in the head.

Also Wednesday, the Federal Institute for Information Access ruled against a decision by prosecutors to keep the files on its investigation into the killings a state secret for 12 years. The institute ruled that prosecutors must turn over investigators reports to an unidentified person who requested them, but said prosecutors could redact the names of people contained in those reports.

Mexican law says authorities can keep some types of sensitive information secret, but not if the case involves serious violations of human rights or crimes against humanity.

On Tuesday, the National Human Rights Commission reclassified the killings as "serious" violations of human rights, after previously referring to them simply as rights violations. The institute cited that reclassification in its decision to order the documents released.

The AP had requested the autopsy reports on the victims' bodies, and both federal and state prosecutors refused to turn them over or claimed they didn't have them.

The Tlatlaya case, along with the disappearance and presumed slaying of 43 students from a rural teachers college in the southern state of Guerrero, have triggered widespread criticism across Mexico about human rights abuses.