The Tlatelolco slaughter leaves deep scars in Mexican society, Amnesty International says. The human rights group called for Mexico's President Felipe Calderon on Thursday to establish the truth behind the deadly crack down on student protestors 40 years ago. Not one person has been sentenced, and no one even knows exactly how many young protesters died.

The failure to deal with the 2 October 1968 massacre, when security forces opened fire on students on the Tlatelolco square in Mexico City, has left a "deep scar" in Mexican society, the rights group said. The massacre remains one of the worst incidents of mass killing in Mexico's contemporary history.

Truth, justice and healing
Despite continuous efforts by victims, relatives and participants in the student movement to uncover the truth of what occurred on the night of 2 October, the full facts have never been established and those responsible have not been held to account.

"President Calderon's government has been all but silent on this dark chapter in Mexico's history," Amnesty International says. The group now calls on the Mexican government to open all relevant archives and records, establish a new and independent inquiry, and lift the obstacles preventing those responsible for the tragedy being brought to justice.

"The deep scar in Mexican society can only be healed by full disclosure, bringing the perpetrators to justice and providing reparations to the victims or their families," said Kerrie Howard, deputy director of Amnesty's Americas programme.

Tlatelolco massacre
On 2 October 1968 La Plaza de Las Tres Culturas (Plaza of three cultures), Tlatelolco was full of people demonstrating against police brutality as part of a general student strike that followed the beating of students by the anti-riot police "los granaderos" in July.

But in the evening the uprising was squashed by police, military and unidentified armed men who surrounded the plaza and opened fire on the protestors. More than 15,000 bullets were reportedly fired into the square that night. The death toll, which included children and bystanders, varies widely. Official documents reported less than 40 while human rights groups estimate between 200 and 350 victims.

"I went back early the following morning and saw piles of belts and shoes. Pools of blood remained on the ground despite obvious efforts to wash them away. I also saw large bullet holes on concrete pillars at adult head height," Javier Zúñiga, a witness of the bloodshed, recounts.

Impunity
Forty years later, impunity continues to surround the massacre. The only high-level official from that period who is still alive and has been identified as one of those responsible for ordering the massacre is former president Luis Echeverría. The 86-year-old, who was interior minister at the time, has been under house arrest since November 2006. He awaits a legal resolution that will indicate whether or not he is to be tried for crimes like the 1968 massacre and others related to the violent repression of dissidents during his years as interior minister.

Late former president Díaz Ordaz, assumed responsibility for the 'incident', although he claimed that the students shot first. He said the student movement "was nothing more than a disgusting alliance of infiltrated conspirators" who spouted communist slogans.

Bloody archives
The governments of the Institutional Revolutionary Party kept official documents referring to the massacre under lock and key. But that did not prevent independent investigations from being carried out, and since the early 1990s efforts to clarify what happened that day have continued, picking up steam after President Vicente Fox took office and a large part of the official archives were opened up to the public.

More than 600 books, documentaries and other films, radio programmes, legal investigations and even university theses and dissertations have been produced on the massacre in Tlatelolco square. All this evidence and testimony could be used in a court of law and to establish a fair historical account.