Mexico City ? The Mexican government on Saturday released a long-awaited report that for the first time officially blamed “the highest command levels” of three former presidencies for the massacres, tortures and slayings of hundreds of leftists from the 1960s to the 1980s.

The report 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 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,” said the report, based partly on declassified Mexican military documents.

The incidents occurred during the administrations of Presidents Gustavo Diaz Ordaz, Jose Lopez Portillo and Luis Echeverria.