A fact-checking investigation undertaken by Breitbart Texas revealed that the video first popped up in the Mexican website Blog Del Narco in 2012 at a time when the Zetas and the Gulf Cartel were having a fierce battle for control of. 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,…