Unconfirmed information released by "The Monitor" indicated that two leaders of the Rojos, Mejía González and Rafael Cárdenas Vela, teamed up to kill Flores Borrego. Cárdenas Vela had held a grudge on Flores Borrego and the Metros because he believed that they had led the Mexican military to track down and kill his uncle Antonio Cárdenas Guillén on 5 November 2010. Other sources indicate that the infighting could have been caused by the suspicions that the Rojos were "too soft" on the Gulf cartel's bitter enemy, Los Zetas. When the Gulf cartel and Los Zetas split in early 2010, some members of the Rojos stayed with the Gulf cartel, while others decided to leave and join the forces of Los Zetas.