Police found the severed head of a two-month-old baby dumped in the town of Delicias in Chihuahua earlier this month in one of the cruelest revenge attacks to scar the state.

"The criminals are hollowing out police and local governments' capacity to uphold the law," said Kevin Casas-Zamora, an analyst at the Brookings Institution in Washington and a former vice president of Costa Rica. "There is an explosion of robbery, extortion, and kidnapping."