Emissaries of Mexican drug cartels are involving themselves more closely in cocaine production in Colombia, paying farmers in advance and pushing cultivation of highly-productive strains, coca growers, security officials and rights activists say.
Top Mexican cartels like Sinaloa and Jalisco Nueva Generacion - which have large areas of influence within Mexico and engage in brutal violence for control of drug routes - have long purchased cocaine from Colombia's guerrilla groups and crime gangs.
