Smith and Martinez apparently went to great and, sometimes, bizarre lengths to obscure their scheme. Federal law requires all slaughterhouses to undergo FSIS inspection. To that end, after meatpacking facilities report their hours of operation to the agency, they are prohibited from working outside those hours.

According to former employees, Smith and Martinez ordered workers to come in on nights and weekends and process meat without inspectors present. To avoid arousing suspicion, workers were instructed to park off-site and work with the lights off, according to court documents. They were also discouraged from leaving the building to take meal breaks, in order to keep activity around the facility to a minimum. Additionally, Smith and Martinez admitted to hiding uninspected meat in freezers, and distracting inspectors from noticing said meat.

Federal inspectors are responsible for making sure that meat products are free from disease, and verifying that processors meet food safety standards. Skip that process and, well, an eater has virtually no idea what is being consumed.

The issue of heart-mixing is a bit more complicated. In February 2017, there was a cacophony of confusion about USDA’s rules regarding the inclusion of cow hearts as an ingredient in ground beef. Technically, heart meat—officially defined as “cardiac muscle trimmed from the ventricular wall of a beef heart”—has always been allowed in ground beef. But the rest of the cow heart, including vessels, fat, and various chambers, are considered byproducts that can not be used. Nonetheless, Smith and Martinez admitted to keeping whole hearts off-site, then bringing them in after hours to process into what they later sold as ground beef.