Catholic priest Marcelo Pérez, an advocate for Indigenous rights and farmworkers in southern Mexico, was killed on Sunday.
Authorities in San Cristóbal de las Casas, Chiapas, reported that Pérez was shot by two gunmen while in his van.
A member of the Tzotzil Indigenous community, Pérez had just completed a Mass when the attack occurred.
He had served the region for 20 years and was known for mediating conflicts in the crime-ridden, mountainous areas of Chiapas.
Pérez had also led several anti-violence marches, receiving numerous death threats as a result.
Chiapas Governor Rutilio Escandón condemned the murder on X, pledging cooperation with authorities to ensure those responsible are brought to justice.