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A Mexican journalist killed on Monday and who gained international fame for taking on cartels and government corruption had gone into hiding for a couple of weeks recently out of fear for his life, said the Committee to Protect Journalists.

Javier Valdez's death in broad daylight came a few weeks after the veteran investigative journalist had told members of the independent nonprofit group, which advocates for press freedom around the world, that he felt tensions were higher than usual among cartel groups fighting for power in the northern state of Sinaloa, said Maria Salazar-Ferro, CPJ’s emergencies director.

“He told my colleague here that it was very tense where he was, he said he had a [tip] for story but that he wasn’t going to do the story, he was going to step back,” Salazar-Ferro told Fox News. “He was nervous and felt he had to leave his home for a bit.”

“He relocated inside Mexico for a few weeks to let things cool down,” she said.

Valdez, for whom threats to his life had become part and parcel of his determination to call out crime and corruption wherever he found it, even was considering leaving Mexico for his safety, Salazar-Ferro said.

“He decided that he didn’t want to pull that alarm quite yet,” she added.

Valdez, 50, is at least the sixth journalist to be murdered in Mexico since early March, an unusually high number even for one of the world’s deadliest countries for media professionals.

Valdez was shot to death in the early afternoon in the state capital of Culiacan, near the offices of the publication he co-founded, Riodoce. State Prosecutor Juan Jose Rios visited the scene and said authorities were investigating all possible motives, including that the killing could have been due to Valdez’s work, though he gave no details.

He was nervous and felt he had to leave his home for a bit. He relocated inside Mexico for a few weeks to let things cool down.

— Maria Salazar-Ferro, Committee to Protect Journalists

Valdez was said to have been driving about a block from Riodoce offices when he was intercepted by gunmen. Valdez was also a correspondent for the national newspaper La Jornada, which reported that he was pulled from his car and shot multiple times.

Images in Mexican media showed a body lying in a street covered by a blue blanket and surrounded by 12 yellow markers of the kind typically used to flag evidence such as bullet casings.

Duncan Wood, director of the Mexico Institute at the Wilson Center, recalled Valdez as a committed, selfless journalist who insisted on beating the drum for justice and rule of law in his homeland.

“He was very very brave, he didn’t hesitate to speak out against those who were doing wrong,” said Wood, who taught in Mexico for 17 years and has served as advisor to Mexican newspapers. “He was very well respected by his peers and he was considered to be an authority in his field and dearly loved by his colleagues.”

Wood and Salazar-Ferro both said they believe Valdez’s cold-blooded killing will put pressure on Mexican authorities to take steps to find the perpetrators, as well as do more to protect journalists.

His death could become an issue in bilateral U.S.-Mexico talks.

— Duncan Wood, director of the Mexico Institute at the Wilson Center

“It’s attracting a lot of attention,” Wood said of Valdez’s death. “The U.S. ambassador in Mexico has made statements. His death could become an issue in bilateral U.S.-Mexico talks.”

Wood said that most homicides in Mexico go unresolved and unpunished. Conviction rates are less than 2 percent for homicides, he said.

“The real problem is the breakdown in the rule of law,” Wood said. “There’s widespread violence in the culture and that is because of the influence of organized crime and the failure of authorities to deal with the situation.”

Many news organizations have simply stopped doing investigative work.

According to CPJ, in 2009 unknown attackers threw a grenade into the Riodoce offices days after it published an investigation on drug trafficking. No one was hurt.

By the group’s count, some 40 journalists have been killed in Mexico for reasons confirmed as related to their work since 1992. An additional 50 were slain during the same period under circumstances that have not been clarified.

Journalists targeted in Mexico are most often local reporters in places where the rule of law is tenuous, but there have also been killings of journalists with national profiles such as Valdez and Regina Martinez Perez, who was slain in 2012. The recent spate of slayings includes Miroslava Breach, correspondent for La Jornada in the northern state of Chihuahua, who was gunned down in March.

On Saturday, seven journalists were assaulted and robbed by a mob of about 100 armed men on a highway in the troubled southern state of Guerrero.

Emilio Gutierrez Soto, 53, knows the dangers of being a journalist in Mexico.

A journalist himself, he fled Mexico nearly 10 years ago after learning that a military officer issued orders to have him killed.

Gutierrez Soto, who lives in New Mexico and has asked the U.S. government for political asylum, said that he felt he had nowhere to turn in his home country. He said authorities routinely harassed him, raiding his home, for instance, without court warrants.

“The government itself is filled with corrupt officials, Javier Valdez’s death must be call to protect press freedom,” he told Fox News. “I was told to stop writing critical stories about the military or I would be killed.”

The Associated Press contributed to this report.