Another reporter has been shot dead in Mexico. Here's how the murders are counted.

Mexican authorities were investigating the killing of a local reporter Monday in the central state of Guanajuato, the country's homicide leader.

The state prosecutor's office identified the victim only by his first name, but local media outlets said the victim was Kristian Zavala, who covered local goings on in the city of Silao on his Facebook page. Zavala and another person were killed Sunday, according to the office. According local media, Zavala and his companion were shot dead by unknown individuals aboard a vehicle after midnight

It was at least the third killing of a media worker so far this year, though it remained unclear if the motive was connected to his work. The U.S.-based Committee to Protect Journalists and Mexico's chapter of Articulo 19 demanded a thorough investigation.