Mexican authorities say they have found the bodies of three decapitated men accompanied by a dead snake and threatening messages.

A report from the state prosecutor's office obtained by The Associated Press says the bodies were found Friday in a car trunk in Culiacan, capital of the Pacific coast state of Sinaloa. They were mutilated and bullet-ridden. The discovery comes just two days after four other decapitated bodies were found in the city.

Authorities say the messages found with the bodies contained threats against Arturo Beltran Leyva, a reputed leader of the Sinaloa drug cartel. They have not identified the victims.

More than 4,000 people have been killed in drug-related violence in Mexico since 2005.