Assailants early Monday burst into the home of the deputy editor of a newspaper in the major port of Veracruz, gunning down the 55-year-old journalist, his wife, and his son.
The executions were the latest in a particularly grim month for Mexican journalists, bolstering Mexico's status as the most murderous place in the hemisphere to work in the media.
The Notiver newspaper in Veracruz where Miguel Angel Lopez Velasco worked as deputy editor, columnist and crime reporter said the gunmen smashed through the front door of the Lopez home with a heavy object around 5:30 a.m., then entered the bedrooms to execute the occupants. Also killed were Mr. Lopez's 21-year-old son, Misael, and his wife, Agustina Solano.
The slayings reverberated far beyond journalistic circles.
Veracruz Governor Javier Duarte de Ochoa said the slaying was a reflection of "the rise of criminality across the country," and pledged to apply "the full weight of the law" against anyone linked to the killing.
Authorities announced no immediate arrests.
Veracruz, the nation's oldest and largest port, straddles a key corridor along the Gulf of Mexico coast for criminal groups that traffic in undocumented aliens and narcotics.
The pace of attacks against journalists is quickening in Mexico.
Monday's killing came just three weeks after authorities found the body of another Veracruz journalist, Noel Lopez Olguin, in a shallow grave on a ranch near Chinameca. Two gunmen snatched Mr. Lopez Olguin, a collaborator for the weeklies Horizonte and Noticias de Acayucan, from his home in March.
The Mexican army said a drug gang leader who'd been arrested confessed to the killing and led soldiers to the shallow grave.
A third reporter, Pablo Ruelas Barraza, was shot to death on June 13 in a small town in Sonora state, bordering Arizona, apparently by two men seeking to abduct him. Mr. Ruelas, 38, worked for two regional dailies.
In another incident, armed men entered a bar June 7 where the news editor of the newspaper Novedades Acapulco, Marco Antonio Lopez Ortiz, 45, was meeting with a friend in the Pacific resort city. They took him away, and he hasn't been seen since.
Mexico's National Human Rights Commission reported late last year that it had tallied 66 murders and 12 disappearances of journalists since 2005.
Mexico maintains a special prosecutor for crimes against the media, but the prosecutor lacks many formal powers to investigate crimes and has successfully brought an average of only one prosecution a year.
In a blistering report earlier this month entitled, Corruption, Impunity, Silence: The War on Mexico's Journalists, the University of Toronto's Law Faculty and the Canada branch of the writers' group PEN International blamed the Mexican government for failing to act with vigor to halt "almost complete impunity" for those who attack journalists.