Three men who worked as photojournalists have been found slain and dumped in plastic bags by a canal in the eastern Mexico state of Veracruz, less than a week after the killing in the same state of a reporter for a newsmagazine, officials said.
Press advocates called for immediate government action to halt a wave of attacks that has killed at least seven current and former reporters and photographers in Veracruz over the last 18 months, most of them among the few journalists still working on crime-related stories in the state.
The deaths have spawned an atmosphere of terror and self-censorship among journalists.
Mexico is one of the world's most dangerous countries for journalists, with reporters and photographers suffering a rising number of attacks in recent years as the country grapples with tens of thousands of killings, kidnappings and extortion against the backdrop of a militarised government offensive against drug cartels.
Prosecutions in the cases are all but unknown, as is the case with almost all homicides and other serious crimes in Mexico.
Local media outlets have been left too intimidated to report on drug-related violence, and social media and blogs are often the only outlets to report on serious crime.
Signs of torture
The latest killings came in Boca del Rio, a town near the port city of Veracruz where police found the bodies of four people on Thursday after passers-by spotted four suspicious black plastic bags in a wastewater canal, the Veracruz state Attorney General's Office said.
The victims bore signs of torture and the bodies had been dismembered, the prosecutor's office said.
One victim was identified as Guillermo Luna Varela, photographer for the news website www.veracruznews.com.mx. Another was identified as Gabriel Huge, who had been working as a photojournalist for the local news agency Notiver.
State officials said the third victim was Esteban Rodriguez, who was a photographer for the local newspaper AZ until last year, when he quit to work as a welder.
The fourth victim was Luna's girlfriend, Irasema Becerra, state prosecutors said.
State officials said the killings bore the hallmarks of organised crime and they would ask federal authorities to help investigate.
Veracruz is a common route for drugs and migrants coming from the south on the way up to the US and much of the area around its main port city on the Gulf of Mexico turned in recent years into a battleground between the Zetas and New Generation, a cartel based in the western state of Jalisco.
The New Generation cartel is allied with the powerful Sinaloa cartel, which is led by kingpin Joaquin "El Chapo" Guzman.
In June 2011, Miguel Angel Lopez Velasco, a columnist and editorial director for the local news agency Notiver, was shot to death in Veracruz along with his wife and one of his children.
Authorities that month also found the body of journalist Noel Lopez buried in a clandestine grave in the town of Chinameca.
Lopez had worked for the weeklies Horizonte and Noticias de Acayucan and for the daily newspaper La Verdad and disappeared three months earlier.
That July, Yolanda Ordaz de la Cruz, a police reporter for Notiver, was found with her throat cut in the state.
Lopez was found after a suspect in another case confessed to killing him, but the other two murders have not been resolved.
The cartel war in Veracruz reached a bloody peak in September when 35 bodies were dumped on a main highway in rush-hour traffic.
Local law-enforcement in the state of Veracruz was considered so corrupt and infiltrated by the Zetas and other criminal gangs that the Mexican federal government fired 800 officers and 300 administrative personnel in the city of Veracruz-Boca del Rio in December and sent in about 800 marines to patrol.
Mike O'Connor, the Committee to Protect Journalists' representative for Mexico, said journalists in Veracruz had exercised an unusual degree of self-censorship even before Ordaz and Lopez were killed, avoiding much coverage of crime and corruption in order to avoid upsetting the Zetas.
"Important news was not covered because it might upset the Zetas. Then these guys were killed and self-censorship cracked down even more," O'Connor said. "Almost all of the police beat reporters left town after those killings."
Regina Martinez, a correspondent for the national magazine Proceso, continued to cover crime-related stories along with a handful of other journalists, however.
On Saturday, authorities went to her home in Xalapa, Veracruz, after a neighbor reported it to be suspiciously quiet. They found the reporter dead in her bathtub with signs she had been beaten and strangled.
Veracruznews director Martin Lara said Luna covered crime news for the Internet news agency and described the victim as a peaceful young man and "a good guy".
Lara said that last year Luna was frightened so badly that he left the state and stopped working for Veracruznews for two months."He got a threat and he had to go."
"Self-censorship was extraordinarily strong but whoever killed these journalists wanted more," O'Connor said. "It still wasn't enough to satisfy whoever killed these journalists."
Mexico's human rights commission says 74 media workers were slain from 2000 to 2011. The Committee to Protect Journalists says 51 were killed in that time. He noted in a statement on the Mexico killings that Thursday was World Press Freedom Day.