MEXICO CITY – An environmental activist who attempted to protect Mexican forests from drug traffickers has been slain along with her 10-year-old son, even though they were under police protection, her associates said Thursday.

Juventina Villa Mojica was killed Wednesday when about 30 gunmen intercepted her police convoy in the mineral-rich hills of southern Guerrero state, colleagues said. Her son, Rey, was also killed, and a 7-year-old daughter survived, the associates said.

Her death follows the recent slayings of at least 15 other local activists, including Villa’s husband last year, in increasingly violent Guerrero. Drug traffickers in the state covet the many virgin forests both for the profitable lumber they yield and the space to plant marijuana and other crops that can be used to produce narcotics.

“They are killing these people for defending the forests,” said Manuel Olivares, an official with the Guerrero Network of Civil Human Rights Organizations.

Villa, thought to be in her 50s, and other activists had recently been in steady contact with the state government, seeking protection and the ability to return to lands they had abandoned out of fear. A big return was planned for Wednesday, which may have prompted the attack on Villa.

As many as 30 state police agents were deployed to protect Villa’s community, and a 10-agent convoy was assigned to accompany her. But it did little good.

“They have been suffering attacks and threats from organized crime which wants to be rid of all the people there,” Olivares said.

None of the agents accompanying Villa were reported killed or injured.

Residents have complained of incursions by the police and army, who claim the region is also a refuge for leftist groups opposed to the Mexican government.

“The murders of Mrs. Juventina and her son could have been avoided if state authorities had heard the clamor of the victims,” the Guerrero-based human rights organization Tlachinollan said in a statement. “The inaction of authorities and the impunity that reigns in the region are the causes of this unstoppable violence.”

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