Most have been killed as rival drug gangs battle for key trafficking corridors into the United States.

-They seek to use beheadings to cow the citizenry from squealing on them and to pressure local authorities to collaborate.
-Fear paralyzes people, stopping them from interfering with their business e.g. by stealing goods. And fear can make people cooperate, e.g. when a cartel seeks to take over an area.

-It is meant to intimidate rivals and send a message to the authorities,” security expert Alejandro Hope told the Associated Press.