But in 2018, Racine’s suburban sprawl on the edge of Lake Michigan became a source of high caliber weapons for one of Mexico’s top fentanyl trafficking gangs, the Cartel Jalisco Nueva Generacion (CJNG), U.S. federal arms-trafficking investigators allege.

The cartel exploited permissive federal and state-level gun control rules to buy some of the most powerful weapons available to American civilians, according to two former agents with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and two other sources, all with knowledge of the investigation.

Members of a local family, working with a cousin in Mexico, enlisted friends and relatives who bought guns on their behalf in Racine and transported them to California and south across the border, according to an indictment from Wisconsin’s Eastern District Court unsealed in February.

The traffickers in Racine and two connected cells in other locations bought more than $600,000 of high-end military-style firearms in under a year, internal ATF documents reviewed by Reuters allege. It seemed like an unprecedented shopping spree, said Tim Sloan, the other former ATF investigator. Sloan was the first to trace a CJNG gun to Racine.