MEXICO CITY (AP) — Javier Valdez was driving in broad daylight down a street he must have known well, just a block from his office, when he became the latest victim of a wave of journalist killings that has hit Mexico.

Masked gunmen forced Valdez from his red Toyota Camry, shot him dead and left his body in the middle of the street Monday, said Riodoce, the publication he helped start.

The car was found later in the afternoon on a sidewalk next to an elementary school, wedged between a utility pole and a wall with the motor still running and the gears engaged.

Valdez, an award-winning reporter who specialized in covering drug trafficking and organized crime, was slain in the northern state of Sinaloa, long a hotbed of drug cartel activity.

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

Reporting on Valdez's killing, Mexican media posted images showing a body lying in the street covered by a blue blanket and surrounded by 12 yellow markers of the kind typically used to flag evidence such as bullet casings. Riodoce said Valdez's laptop and cellphone were missing.

Prosecutors announced they were investigating whether the killing may have been due to Valdez's work or a carjacking turned deadly. President Enrique Pena Nieto condemned what he called an "outrageous crime."

Valdez, also a correspondent for the national newspaper La Jornada, was an internationally recognized journalist who authored several books on the drug trade.

He was considered a rare source of independent, investigative journalism in Sinaloa, said Jan-Albert Hootson, the Mexico representative for the New York-based Committee to Protect Journalists.

"And for that same reason, he and his magazine and his co-workers were always under threat of violence," Hootson said.

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.

Sinaloa has long been a drug trafficking center and is home to the Sinaloa Cartel headed by notorious kingpin Joaquin "El Chapo" Guzman, who is in a New York prison awaiting trial on multiple charges. Experts say Guzman's arrest last year and extradition in January have led to upheaval in the area as rival factions war for control of the gang.

"Drug trafficking there is a way of life," Valdez said in an October interview with Rompeviento TV. "You have to assume the task that falls to you as a journalist — either that or you play dumb. I don't want to be asked, 'What were you doing in the face of so much death ... why didn't you say what was going on?'"

Hootson described Valdez as a warm, friendly man, well-liked by other journalists who frequently sought his help to navigate and understand the complex, dangerous state.

"His door was always open. ... Everybody always deferred to his knowledge," Hootson said. "And in that sense, it's a huge loss for everybody."

Valdez was recognized with the International Press Freedom Award in 2011 by CPJ, which released a report this month warning that widespread impunity leaves journalists vulnerable to attacks in Mexico.

Last Wednesday, the federal Attorney General's Office replaced the head of its division responsible for investigating journalist killings. Ricardo Sanchez Perez del Pozo, a lawyer with a background in international law and human rights, took over the post.

Peter Orsi on Twitter at www.twitter.com/Peter_Orsi