Second large seizure of fentanyl at Mexico City airport

Mexican marines and customs authorities said Tuesday they seized 250 pounds (113.5 kilograms) of the synthetic opioid fentanyl at the Mexico City airport, the second such large bust there this month.

Authorities said the fentanyl was found by trained dogs in four small cardboard drums that were part of an air freight shipment.

Mexican drug cartels once favored importing fentanyl and closely related chemical precursors from Asia through Mexico's Pacific coast seaports, but they now appear to be turning to airports as well.

In mid-August, customs authorities seized almost 500 pounds (220 kilograms) of a chemical used to make fentanyl at a cargo terminal at the Mexico City airport. That shipment came on a flight from Spain, an unusual source for the drug, suggesting Mexican traffickers may be having a harder time getting their hands on fentanyl and precursors from their usual suppliers in Asia.

In mid-July, the government announced the military was taking over control of Mexico’s land and maritime ports of entry to root corruption out of the country’s customs offices.

Mexican traffickers usually perform final chemical steps to make fentanyl, which is many times stronger than heroin. They generally cut it, press it into counterfeit pills and smuggle it into the United States. Traffickers have also been mixing fentanyl into heroin to make it stronger.