After six people were massacred in southern Colombia, authorities said the killing could be a sign of trouble brewing within the organization of one of the country’s most powerful drug lords.

On June 1, a group of gunmen pulled up to a soccer pitch just outside of Villavicencio, Meta, and opened fire. Among those killed during the shootout were a communications staffer for Ecopetrol, the state-owned oil company, and a taxi driver.

Authorities say that the intended victim of the massacre was alias “Mojarro,” accused of working for one of Colombia’s most wanted men, Daniel Barrera, alias “El Loco,” or “the madman.” Mojarro, whose last name is reportedly Saldarriaga, is a local crime lord in southern Meta, smuggling arms, drugs and running a transport company that served as a cover, according to Cali-based newspaper El Pais.

According to authorities, Barrera may have orchestrated the hit against Mojarro because he is increasingly fearful that his former confidants could be clandestinely negotiating his surrender. Barrera is one of the most wanted drug traffickers in Colombia, with a reward of five billion pesos ($2.5 million) on his head in Colombia, plus five million dollars from the U.S. government.

There is evidence that the pressure is rising against Barrera’s associates. One of Barrera’s closest operatives, Julio Alberto Lozano, surrendered to U.S. authorities in Panama in November 2010. Another alleged business partner, Ignacio Alvarez Meyendorff, was arrested in a Buenos Aires airport in April. These two captures could indicate that Barrera has good reason to fear that members of his inner circle are under pressure to give key intelligence to law enforcement.

But suspicion might not be the only motive behind the Villavicencio killings. The massacre was obviously carried out by non-professionals who were not even able to identify Mojarro at the scene: he managed to escape untouched, although two of his alleged bodyguards (former police officers, according to national newspaper El Tiempo) were killed. It is possible that Barrera ordered the hit because Mojarro was suspected of mishandling a drug shipment, perhaps selling the product to another buyer without Barrera’s approval. There are plenty of reasons for Barrera to be particularly nervous about how his product is handled, which may explain why it he felt it necessary to make a point through extreme violence.

Mojarro was allegedly close to Pedro Oliveiro Guerrero, alias “Cuchillo,” the deceased leader of the Popular Revolutionary Anti-Terrorist Army of Colombia (Ejercito·Revolucionario Popular·Antiterrorista·Colombiano – ERPAC). Barrera has a business partnership with the ERPAC, buying most of his cocaine from the organization before shipping it on to the European market.

But the ERPAC has been on shaky ground since Guerrero was killed during a police raid on his country ranch last Christmas. The group’s newly appointed leader, Jose Eberto Lopez Montero, alias “Caracho,” allegedly once worked in one of Colombia’s most rural and coca-rich departments, Vichada, where he coordinated drug shipments on Barrera’s behalf. So there is some reason to believe that Lopez had the contacts and the business acumen to maintain the group’s good relationship with Barrera.

But Barrera has other reasons to be nervous about the source of his product. Barrera enjoyed Guerrero’s trust partly because the two coordinated the killing of a common rival, paramilitary warlord Miguel Arroyave, in September 2004. Barrera and Lopez Montero have no such bond.

Additionally, one of the foundations of the Barrera-ERPAC alliance was Barrera’s ability to negotiate a pact with the Revolutionary Armed Forces of Colombia (Fuerzas Armadas Revolucionarias de Colombia – FARC) in eastern departments like Vichada. The ERPAC clashed heavily with the FARC when the drug gang first advanced into the department in 2008, attempting to take over the rebels’ monopoly on the sale of coca base. Acting as an intermediary, Barrera negotiated a business alliance between the FARC and the ERPAC which still stands today: the rebels sell coca base, while the ERPAC processes it into cocaine and passes it on to Barrera’s international network.

With Guerrero dead, the FARC-ERPAC alliance has managed to hold, with one key exception. In February, a faction of the ERPAC switched sides and began working as full time mercenaries for the FARC’s 1st Front in Guaviare department. This may have caused concern, both for the ERPAC and Barrera, that more factions would begin to splinter off and perhaps descend into infighting. Such instability would spell bad news for Barrera’s cocaine business. With the threat of the ERPAC falling apart into undisciplined factions, Barrera would be less willing to tolerate infractions elsewhere — which may have been the cause of the Mojarro-related killings.

Mojarro might have angered Barrera by attempting to pass on intelligence to the authorities. But it is also possible that this massacre is another case of payback after a drug sale went awry. Barrera, after all, has many reasons to fear that the main source of his product — the ERPAC and the FARC — may soon become less than reliable. This would make other cases of insubordination even less tolerable.