I don't know about cults, but the state department web page lists Matamores as one of the cities where drug gangs have been fighting each other over control of who gets to run the drugs across the border. There have been killings and kidnappings associated with this activity in almost all the large border cities from California to Texas. Tourists have been advised to only cross during business hours and avoid drug and prostitution areas because of this.
This guy took advangage of the recent criminal activity to try to get away with murder. The state dept claims that the people kidnapped and killed were all associated with drugs or prostitution, or were in locals not associated with crowds and tourism. So this should reduce the fear many of us have about random crimes over the border. The state department article did little to quell my fears, as they explained how lawless Mexico is in very graphic terms. (I have already crossed Jamaica off my list, now maybe Mexico too?)
That's also what the Mexican government always uses as an excuse for the over 400 Juarez murders of women and girls --- plus a whole lot more men --- over 1000 men and boys killed in the same time frame. They aren't all druggies and prostitutes. Laredo's Missing