Monday marked the fourtieth anniversary of a dark day in the history of football in Argentina and, indeed, across South America. On the 23rd June 1968, as Boca Juniors fans left the Estadio Monumental at the end of a mid-season superclásico, a gate was left less than fully opened under circumstances that remain mysterious to this day, and the result was 71 deaths: the highest death toll of any of Argentina’s stadium disasters.

When the fans making their way down from the top of the Tribuna Centenario reached the final flight of stairs, there was a sudden rush down the stairs and fans towards the front tried to get out of the way by running for the exit. The gate, however, was obstructed, either closed altogether or left only partially open, and the turnstiles hadn’t been moved out of the way: it isn’t clear even today exactly what the situation was, much less what caused it.

As this memorial report in El Gráfico tells us, some survivors also spoke of how the police, mounted on horseback, compounded the situation by insisting that those who’d already made it through the gate re-enter, further congesting the only escape route. Seventy-one died and the walls around the gate were stained with blood.

Two months later, two River Plate directors, Américo Di Vietro and Marcelino Cabrera, were sentenced to jail for negligence after a trial regarding their roles in running the stadium’s security operation. At the end of November that year, however, both men were cleared on appeal. The following year, the case was archived, and the file hasn’t been reopened since.

Ten years and two days after that, the Monumental saw one of its greatest celebrations, as I’ll be writing on Wednesday. But three decades on from that, the events of ten years prior to Argentina’s World Cup win are still seared into the collective memory of the nation.