Violence has soared in Sinaloa since the capture in the U.S. of cartel co-founder Ismael "El Mayo" Zambada almost a year ago.

Prosecutors in northern Mexico’s Sinaloa state are investigating the discovery of 20 male bodies with gunshot wounds – including five that were decapitated – on a bridge over a federal highway.

Four decapitated bodies were found hanging from a bridge in the capital of western Mexico's Sinaloa state on Monday, part of a surge of cartel violence that killed 20 people in less than a day, authorities said.