The dismembered bodies of the 22-year-old Martinez and 23-year-old Julian Alejandro Zamora Gracia were found Wednesday in Los Arcos, a neighbourhood in the southern section of Saltillo, the Coahuila state Attorney General's Office said.
The victims' identification was missing when the bodies were discovered, the AG's office said.
Martinez worked for the society pages of La Vanguardia and had been hired just a month ago, last reporting Tuesday to get his assignments, the newspaper said.
The photojournalist failed to show up Tuesday afternoon to cover a story he had been assigned, prompting "company personnel to try, unsuccessfully, to locate him with the assistance of relatives and friends", La Vanguardia said in a front-page story.
An International Press Institute, or IPI, and World Association of Newspapers and News Publishers, or WAN-IFRA, delegation visited Mexico in February and called for more protection for journalists.
Both the IPI and Reporters Without Borders, or RSF, ranked Mexico as the fourth most dangerous country in the world for journalists in 2012, trailing only Syria, Somalia and Pakistan.