Domínguez Rodríguez, who was an independent reporter for a local newspaper in the northern border town of Nuevo Laredo, was stabbed two dozen times in front of relatives on Jan. 13.

Mexican prosecutors said that Domínguez Rodríguez’ death may have been related to his journalistic work, but not to organized crime since he did not cover that beat.

A statement from the Attorney General’s Office said that “the results … indicate a probable link between these events and the exercise of freedom of expression,” and that the motive for the killing was still under investigation.

Although the names of the suspects have not been released (in accordance with Mexican law that prohibits publicly incriminating people until they have been  found guilty), local authorities said that at least three of the six suspects “worked in the information industry.”

Later in the day, prosecutors in the coastal state of Veracruz announced the 25-year sentencing of two former police officers for the 2015 murder of another journalist, Moises Sánchez Cerezo.

Mexico is one of the most dangerous countries in the world for journalists and among the ones with the highest levels of unsolved crimes against the press.