At about 2am on November 16, 1989, Salvadoran soldiers burst into the home of six Jesuit priests teaching at the University of Central America. They proceeded to slaughter them.
Father Ignacio Ellacuria was the main target, according to evidence gathered after the 1992 peace accords that ended the long civil war in El Salvador.
Since the 1980 assassination of Archbishop Oscar Romero, Ellacuria had been the Catholic church's most outspoken defender of the poor, offending the Salvadorian military.
"He had been hated by them since the very beginning of the war", Father Tim McMahon, who had worked in El Salvador with the priests, told the November 6 Kansas City Catholic Key newspaper.
"He picked up the role of Romero, and kept demanding a just peace", he said. "They couldn't shut him up or disprove him, so he had to be wiped out."
The other priests, Ignacio Martin-Baro, Segundo Montes, Amando Lopez, Juan Ramon Moreno and Joaquin Lopez y Lopez, were all murdered to eliminate witnesses. Their housekeeper, Julia Elba Ramos, and her 15-year-old daughter Celina, who had chosen to stay that night at the priests' residence for safety, were killed in their beds.
It is estimated that more than 75,000 people died in the liberation struggle in El Salvador, which was characterised by extreme brutality committed by military death squads.
"The real cause of the civil war was unbridled selfishness and greed, and brutal oppression", McMahon said.
"Entire villages had been massacred and wiped from the face of the earth. Thousands of ordinary folks had been killed. Finally, when the military ordered the murders of six priests, the world got shocked."
The Jesuits were renowned for teaching at the university during the week and then spending their weekends ministering in the countryside to the poor. They were popular for advancing the radical ideas of Liberation Theology.
Jon Sobrino, a priest who survived the attack because he was out of the country at the time, returned to El Salvador and has continued as a liberation theologian, writing such books as The Principle of Mercy: Taking the Crucified People from the Cross.
In 2007, the Vatican reprimanded him and said his ideas were "erroneous or dangerous and may cause harm to the faithful".
Two military officers, including Salvadoran army colonel Guillermo Alfredo Benavides Moreno, were convicted of organising the murders, after an international campaign demanded justice.
The US Congress passed a motion of remembrance for the six murdered priests, and Julia Elba Ramos and Celina Mariset Ramos, on September 22. None of the many US officials who helped fund, train and organise the Salvadoran death squads have ever been charged.