Question: which Mexican drug cartel does its member murdered John Clay Walker 
Sentence (from "Servando Gómez Martínez"): Servando Gómez Martínez (born February 6, 1966), commonly referred to by his alias La Tuta (The Teacher) for once being a teacher, is a Mexican drug lord and former leader of the Knights Templar Cartel, a criminal organization based in the state of Michoacán.
Relevant evidence: No