Gunmen shot and killed a Mexican community police figure who led teams of volunteer search parties looking for the missing 43 students in the state of Guerrero, a place Miguel Angel Jimenez frequently referred to as one great "cemetery."
Jimenez was shot early Saturday in his taxi in his hometown of Xaltianguis, north of the resort city of Acapulco.
The 45-year-old was a member of the Guerrero state community police force known by its acronym UPOEG. The UPOEG and other teams of volunteers began leading search groups into the hillsides around the city of Iguala, almost immediately after the Sept. 26 attacks that left six people dead and 43 missing.
Jimenez appears in "The Missing 43," the VICE News documentary that chronicled the case of the Ayotzinapa Normal School students and the protest movement it sparked around the world.
In one scene, he is leading a group of unarmed volunteers to examine possible mass graves and receives an anonymous warning.
"One of our guys just got a phone call. Someone is threatening us," Jimenez says in the footage, which was shot in October 2014. "He said he had orders to kill all the innocent people."
In another moment, he coaxes an old farmer for information about possible graves, saying: "We are not the government."
According to reports in the Mexican press, Jimenez had some time ago returned to the southern coastal region of the state. There, the UPOEG is in conflict with a rival vigilante force known as FUSDEG, which reportedly split off from UPOEG in August 2014.
A shootout between the groups left four dead in March. The rivals accuse one another of corruption and for other killings.
Related: None of Mexico's Missing 43 Students Are Among 129 Bodies Found in Mass Graves
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Jimenez's murder occurred amid another bloody weekend in one of Mexico's poorest and most violent states. Fifteen people were killed overall, Reuters reported.
Acapulco has become the most violent city in Mexico and is known as the third most violent in the world.
Meanwhile, in the Guerrero municipality of Olinalá, twenty people were allegedly kidnapped on Sunday, according to a separate community police force that is also linked to the jailed Mexican American local leader Nestora Salgado.
News account said the 20 were taken by a political group tied to the ruling Institutional Revolutionary Party (PRI), but the report had not been independently confirmed by Monday.
Salgado, jailed since August 2013, stood in court once more on Monday morning in Mexico City for a hearing regarding her possible release.
At least 129 bodies have been unearthed in clandestine graves around Iguala since the Sept. 26, 2014 attacks on the students. Volunteers looking for scores of loved ones who are missing in Guerrero separated themselves from the community police groups earlier this year.
"We'd go without security, we'd risk ourselves along with a few families with Miguel," Mario Vergara, who has been looking for a missing brother since November, told VICE News on Monday.
"Miguel was a great motivator. He taught us how find graves," Vergara said.
Related: Hunger Strike Called Off by American Woman Jailed in Mexico After Starting Citizen Police Force
Rafael Castillo contributed to this report. Follow Daniel Hernandez on Twitter: @longdrivesouth