José Manuel Sierra Sabogal, alias “Zarco Aldinever,” second-in-command of the Second Marquetalia (Segunda Marquetalia), was allegedly killed in an August 5 ambush in the southern reaches of the Colombia-Venezuela border, according to a statement from the group. The Second Marquetalia is a dissident group of former fighters from the Revolutionary Armed Forces of Colombia (Fuerzas Armadas Revolucionarias de Colombia — FARC), also known as the ex-FARC Mafia.

The statement accused the National Liberation Army (Ejército de Liberación Nacional — ELN) of carrying out the attack using explosives and said it also claimed the lives of four other fighters. However, Colombian authorities have so far been unable to independently verify the claims.

*Sierra Sabogal’s death, which occurred during an ELN attack near the Colombia-Venezuela border, was confirmed on August 11 by Colombia’s Defense Minister, Pedro Sánchez.

The Second Marquetalia accused “Pedro Pablo” or “Copete,” commander of the José Daniel Pérez Carrero Front of the ELN’s Eastern War Front, of orchestrating the ambush. He allegedly invited high-ranking members of the Second Marquetalia to a meeting to lure them into the ambush.

“The ELN acted with malice and treachery. They carried out premeditated simultaneous attacks on other Second Marquetalia units located in the region,” the group said in the statement.

The killing is linked to a series of recent armed confrontations between the ELN and Second Marquetalia in the municipality of Maroa in Venezuela’s Amazonas state, which local sources began reporting to InSight Crime on August 3. The battles between both groups, according to those reports, took place along the border with the Colombian department of Guainia.

Colombian President Gustavo Petro confirmed the armed confrontation between the guerrilla groups. “The ELN has entered into war with the Second Marquetalia and their conflict extends into Venezuela, where they have already killed people,” the president said in a post on X.

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Before this fighting, both the ELN’s Eastern War Front and the dissident Acacio Medina Front, an ally of the Second Marquetalia, had maintained certain financial arrangements and territorial divisions along this part of the border. This allowed them each to manage the area and oversee illegal mining in Amazonas, as well as the drug trafficking routes that cut through this area.

Zarco Aldinever had been in the crosshairs of Colombian authorities. They accused him of being one of the main suspects behind the June shooting of Senator and presidential candidate Miguel Uribe Turbay in the capital city of Bogotá.

The breaking down of the guerrilla alliance in this strategic border region may lead to further military advances from the ELN and spark a new conflict with major implications for both Colombia and Venezuela.

After Hugo Chávez became Venezuela’s president in 1999, he welcomed many FARC commanders into the country who went on to establish operations in several border states. However, when President Nicolás Maduro rose to power in 2013, he established more favorable relations with the ELN. With the tacit support of his regime, the ELN began to expand its operations across the border, eventually displacing some of the dissident FARC factions still there.

The latest flare-up between the ELN and ex-FARC Mafia comes about eight months after the start of another conflict between the guerrilla groups. In January 2025, the ELN launched a violent assault on the ex-FARC’s 33rd Front in the contested Catatumbo region, which is one of the world’s top cocaine-producing areas.

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With the ELN also controlling key territory on the Venezuelan side in the state of Zulia, this cemented the guerrilla group as the top armed actor on the northern part of the border, granting them access to drug trafficking routes leading to dispatch points in Venezuela.

The ELN’s latest confrontation with the Second Marquetalia in the south suggests this may be the next key battleground for control of the border.

Unlike prior fighting, this conflict may develop more on the Venezuelan side. That is largely because the ex-FARC Mafia’s Acacio Medina Front has more military capacity on that side and can rely on more than a decade of experience operating there. Illegal mining in Amazonas and the drug trafficking corridors near Brazil represent hugely important financial resources for both groups, making it unlikely that either will cede control without a fight.

There is also the risk that the confrontation could expand further north into Venezuela’s Apure state, which borders the Colombian departments of Arauca and Vichada. The Second Marquetalia maintains a strong presence there, particularly in the town of Elorza in the municipality of Rómulo Gallegos. This has long been the preferred place for ex-FARC commanders to operate, and they have taken over ranches and set up camps in the region.

The alleged killing of Zarco Aldinever would add him to a growing list of FARC dissidents killed in Venezuela. Other infamous commanders killed there include Miguel Botache Santanilla, alias “Gentil Duarte,” Seuxis Pausías Hernández Solarte, alias “Jesús Santrich,” Hernán Darío Velásquez Saldarriaga, alias “El Paisa,” and Henry Castellanos Garzón, alias “Romaña.” The Second Marquetalia’s top leader, Luciano Marín Arango, alias “Iván Márquez,” was also gravely injured in Venezuela.

This article, written by the Venezuela Investigative Unit, was originally published by InSight Crime, a Medellín-based foundation dedicated to the investigation and analysis of crime and security in Colombia and Latin America. It has been generously shared with Finance Colombia under a Creative Commons license.

One person was captured with the total of 1,216 kilograms of ore, that according to the Colombian prosecutor’s office may be worth as much as 453,000 USD. Coltan is an ore containing rare-earth metals like tantalum and niobium, useful in the manufacture of electronics and metal alloys.

There are legitimate mining operations of rare earth metals in Vichada, such as the recent activity by Auxico Resources, though the mining of Coltan illegally by armed insurgents is a troubling sign of new diversification into areas that put at risk the local indigenous populations, the environment, and the freedom of these remote areas from organized violence. As has been experienced in Colombia’s gold producing areas, illicit actors can put legitimate operations at risk.