It was a fracture between the old School Zetas and the Trevino clan. I'm not sure of the reason (haven't really read about it) but the Trevino clan wanted to focus more on intelligence than brute force and they know the shock tactics don't work in the long run or even short term so they went through a transformation and changed their name to Cartel del Noreste while the Old School Zeta bosses retain their name. It was to clense their image and reputation now they have a group called the "Katas" that operate in Nuevo Laredo like the CIA or mini CIA giving intelligence to the commanders or captains and so on. They generally keep the Marines and Mexican soldiers/army at bay and guessing. They had intelligence before(like other cartels) but they took this to new levels. It's really shocking on it's own.

*It was a fracture between the Old School Zeta (boses) and the Trevinos.

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