Rogers Devia, a former mayor in central Colombia who had aligned with presidential candidate Abelardo de La Espriella, was shot dead Saturday in an attack in the rural area of Cubarral, local authorities said. The Public Defender’s Office of Colombia’s Meta department said Devia died along with his aide, Eder Cardona.

The killings, which took place in Cubarral, come as Colombia prepares for a presidential election on May 31. The Public Defender’s Office said the incident could undermine “the exercise of political rights and democratic participation,” warning that such violence can affect how candidates campaign and how voters participate in the process.

Devia served as mayor of Cubarral from 2020 to 2023, according to the Public Defender’s Office posting. Cubarral lies about 170 kilometers (105 miles) south of Bogotá, placing it in the country’s central region.

De La Espriella represents the National Salvation Movement, and Devia was described by AP as being allied with the presidential bid. The report said the attack was the latest in a series of political-violence incidents in a region contested by armed groups, including groups the U.S. government labels as terrorist organizations and a third group described as a splinter of the former dominant FARC.

Colombia’s Interior Minister Armando Benedetti said on social media that investigators did not yet know why Devia was attacked. Benedetti also said police had recently stopped an attack against a staffer of another presidential candidate, Paloma Valencia, in Cubarral.

The May 31 election will be contested by at least half a dozen candidates, including two candidates from smaller left-wing parties. If no candidate receives 50% of the votes, a runoff will take place in June between the top two contenders.