Icons include Jesus Malverde, the patron saint of drug traffickers, and Santa Muerte, or Death Saint, a skeletal figure of a black-cloaked woman with a scythe.
Almonte said he investigated a case in Tijuana where a drug gang cut off the head of a victim as a Death Saint offering.
He said underworld saints have gained popularity among U.S. smugglers of non-Mexican origin as drug networks controlled by Mexican gangs expand their territory.