Paraguayan officials have arrested a man accused of participating in acts perpetrated by the Paraguayan People’s Army (EPP)—an armed group that officials say has ties to Colombia’s Fuerzas Armadas Revolucionarias de Colombia (FARC). José Villalba was taken into custody in Concepción (a city near the Brazilian border) during an operation by the national police and armed forces. He is the brother of the man believed to be the EPP’s principal leader.

Mr. Villalba is the 10th person to be arrested in recent weeks in connection to the kidnapping of Fidel Zavada, a prominent rancher who was allegedly held by the EPP for 94 days before being released for a $550,000 ransom.

Officials say that the EPP is a splinter group of the Free Motherland Party (PPL), which was involved in the 2005 kidnapping and murder of Cecilia Cubas, the daughter of a former Paraguayan president. Up to a dozen individuals who are also suspected of being members of the group have been spotted in remote jungle areas near the site of Villalba’s arrest. Officials say they are carefully monitoring the group’s movements and are likely to make more arrests soon.