According to Dudley's hypothesis, the Zetas attacked the Casino Royale and other gambling centers in Monterrey, because these places were connected to the Gulf Cartel.
5. 49 Mutilated Bodies in Cadeyreta, Nuevo Leon, May 2012
On the 13th of May, 2012, Mexican police found 49 mutilated bodies on a road that leads from Monterrey to the U.S. border, in the municipality of Cadereyta. A letter "Z" was spray-painted on a wall near the site where the bodies where found, but the Zetas denied they had committed this atrocity.
A week later however, Mexican officials arrested a Zetas member that was allegedly linked to this incident. His name is Daniel de Jesus Helizondo Ramirez, but he is more widely known as "El Loco." El Loco told Mexican officials that he had been told to dump the bodies in Cadereyta by the Zeta's second most important commander Miguel Angel Treviño.
Insight Crime notes that it is strange for the Zetas to deny a crime, and then confess to it. The website believes that the massacre could have been committeed by a local cell of the Zetas that acted without the blessing of top officials from the gang. Another possibility, according to Insight Crime is that top leaders of the gang did authorize the killings, but then wanted to disassociate themselves from the incident, due to the government's strong response.