The severed heads of four men were found dumped on a Mexican street yesterday with a message accusing a drug gang kingpin of treachery, police said.
Residents in the northern city of Culiacan found the men's bodies wrapped in plastic sheets and a blanket, with their heads stuffed into white plastic bags.
An obscenity-laden note scrawled onto a piece of cardboard invited Joaquin "El Chapo" (Shorty) Guzman - the head of the Sinaloa drug cartel - "to see what his stupid acts had caused."
Guzman, who is considered Mexico's most-wanted man, is battling a rival gang led by his one-time ally Arturo Beltran Leyva, whose hitmen reportedly killed one of Guzman's sons in May.
In a separate incident in the same city, police said they killed four suspected drug gang members in a shootout.
More than 1,600 people have died so far this year in drug violence as gangs battle for control of lucrative trafficking routes and as the government has stepped up anti-smuggling operations by deploying thousands of army troops.