MEXICO CITY — Among the many horrifying videos posted online amid Mexico’s drug cartel violence, few have been as profoundly shocking as that of a 14-year-old boy kidnapped in late October along with about a dozen family members in the country’s south.

Authorities confirmed on Friday that 14-year-old Ángel Barrera Millán was one of four minors and seven adults whose dismembered bodies were found dumped this week.

The deaths underscore the brazen power of the local drug cartels and the powerlessness of the government in the area around Chilpancingo and the nearby township of Chilapa.

“The state authorities have allowed these organized crime groups to gain very deeply rooted control of these areas,” an activist of the human rights group Tlachinollan said on condition of anonymity, for fear of reprisals. “This area is completely controlled by the Ardillos.”

It is not clear what happened to the other two members of the group — 13 disappeared and 11 bodies were found, including three women and another boy who was 13.

— The Associated Press