Ten retired members of Colombia's military began admitting to victims' families on Tuesday their roles in the assassination of 120 civilians that were later presented as rebels killed in combat.
It was the first public admission by the former soldiers that they had made people disappear before killing them in cold blood.
One general, four colonels and five officers, as well as a civilian, were due to make their confessions to the special tribunal set up as part of the 2016 peace deal that ended a half century of conflict between the government and Revolutionary Armed Forces of Colombia (FARC) rebels.
The "false positives" scandal in which murdered civilians were passed off as enemy combattants is the largest ever to have rocked Colombia's armed forces.
"I ask you to clear our family names ... they were rural workers, not subversives, guerrillas and thugs as they were branded," said Eduvina Becerra, the partner of Jose Ortega, a murdered farmer.
Around 50 of the victims' family members showed up to the university theater in Ocana, close to Colombia's northern border with Venezuela, where the Special Jurisdiction for Peace (JEP) hearing took place.
"I acknowledge and accept my responsibility as co-perpetrator" of the murders that took place between 2007 and 2008, said Nestor Gutierrez, a former non-commissioned officer in the army.
"We murdered innocent people, peasants," said Gutierrez, promising to "clarify it here before the judgment, before the world, before the country."
In front of an audience of sobbing family members, the soldiers gave details about how they murdered the victims, most of whom were men aged 25 to 35.
The JEP, which was set up in 2017 to try the worst atrocities committed during the conflict, said that Ocana was the site of a sinister plan thought up by a battalion stationed in the town of 100,000 and motivated by "the army's institutional policy of counting bodies" to inflate the reporting of their successes in combating guerrillas and other armed groups.
The tribunal says more than 6,400 civilians were murdered between 2002 and 2008 after being lured to areas far from their homes.
The JEP has the authority to offer alternatives to jail time to people who confess their crimes and make reparations.
The Catatumbo region where Ocana is located is home to the largest area of illegal coca leaf crops used to make cocaine in the world, making it a hub for organized crime.
The hearing is due to last two days with former general Paulino Coronado the highest ranking officer on trial.