In the latest example of Mexico's warring drug cartels taunting each other with gruesome on-line videos, footage posted on a popular cartel-tracking blog shows members of the Gulf cartel interrogating and then beheading at least three members of the Zetas cartel.

The grainy three-minute video, which appeared on Mundonarco.com Wednesday, depicts five shirtless men on their knees, their chests painted with large black "Z"s, surrounded by masked members of the Gulf cartel wielding machetes.