Colombia and Venezuela have reached an agreement to search for remains of victims who were killed by paramilitaries during Colombia’s internal armed conflict and reportedly buried in Venezuela, Colombia President Gustavo Petro said on Tuesday.

The agreement follows recent confessions before the Special Jurisdiction for Peace (JEP) tribunal by former paramilitary commander Salvatore Mancuso, Petro said.

The JEP was created under a 2016 peace deal with the now demobilized FARC rebel group to try former combatants and members of the military.

“We’re going to do all the work we can with our body identifying experts. Colombia has history in this experience,” Petro told journalists on the sidelines of a summit of South American Presidents in Brazil’s capital, Brasilia.

“If Mancuso manages to find those areas, if there really are bodies there, the Venezuelan state could help us return the remains to their families,” Petro added.

Colombia’s internal armed conflict has run for almost six decades, killing hundreds of thousands of people and displacing millions more.

Tens of thousands have been disappeared during the conflict, fought between Marxist rebels, government troops, and right-wing paramilitaries.

A number of Colombian victims killed by paramilitaries were buried on the Venezuelan side of the countries’ shared border, Petro said, citing Mancuso. He added that the clandestine burials helped cover up the “genocide” which took place in the region.

Paramilitary groups emerged in the 1980s, funded by ranchers, landowners, merchants and drug traffickers eager to defend themselves from attacks by leftist guerrilla groups.

The groups – accused of widespread human rights violations including murders, rapes and torture – demobilized under a peace deal during the term of former President Alvaro Uribe, though many members later formed crime gangs.

-Reuters (Reporting by Oliver Griffin and Luis Jaime Acosta)