A long-awaited Mexican government report blames "the highest command levels" of three former presidencies for the massacres, tortures and slayings of hundreds of leftists from the 1960s to the early 1980s.
Based partly on declassified Mexican military documents, the report posted on the Internet on Saturday ends a five-year investigation by a special prosecutor named by President Vicente Fox to shed light on past crimes, including a 1968 student massacre and the disappearance of hundreds of leftist activists in the 1970s and early 1980s.
The report states that "the authoritarian regime, at the highest command levels," broke the law and "committed crimes against humanity" that resulted in "massacres, forced disappearances, systematic torture and genocide to try to destroy a sector of society that it considered ideologically to be its enemy."
Special prosecutor Ignacio Carrillo, who was appointed in November 2001, handed his report to Mexico's Attorney General's Office late on Friday. The report was later posted on the Internet for the public, and Carrillo said it would presented at a ceremony with Fox before he leaves office.
The incidents occurred during the administrations of presidents Gustavo Diaz Ordaz, Jose Lopez Portillo and Luis Echeverria.
Asked by reporters if the presidents knew of the atrocities but did nothing, Carrillo replied, "Yes."
Carrillo said the report is only the beginning -- that the Mexican government must prosecute those responsible if it is to prevent such atrocities from occurring in the future. The state also must compensate victims' families, he said.
"This was not about the behavior of certain individuals," Carrillo said. "It was the consequence of an authorized plan to do away with political dissidents."
Until now, many of the cases consisted of little more than witnesses' accounts.
Kate Doyle, a Mexico expert at the Washington-based National Security Archive, a private, nonpartisan research group, said the report is a "powerful development" because for the first time the government "officially lays the blame at the feet of three Mexican presidents."
It "clearly describes in detail how the authoritarian regime" of the Institutional Revolutionary Party, or PRI, "used violence to silence the opposition," while painting an image to the world that it was running a democracy, she said.
Fox vowed to prosecute Mexico's past crimes when he was elected in 2000, ending 71 years of PRI rule.
But the courts have repeatedly blocked Carrillo's efforts to detain Echeverria, the only implicated president who is still living.
Carrillo denounced "the bad conduct of legislators and judges over the years who have promoted impunity with their false distortions of the law and reforms."
In July, a federal judge threw out genocide charges against Echeverria, ruling that a 30-year statute of limitations had run out. Echeverria, 84, had been under house arrest for more than a week on charges that he organized a student massacre as interior secretary in 1968. The charges were the first to have been filed against a former president.
The massacre took place in Mexico City's Tlatelolco Plaza on Oct. 2, just before the capital hosted the Olympics. Officials said 25 people were killed, though human rights activists say as many as 350 may have died. The attack is considered one of the darkest moments of PRI rule.