The growers who are set to plead guilty to federal criminal charges related to the deadly 2011 listeria outbreak linked to their cantaloupe are suing Primus Labs alleging that company’s subcontracted auditor gave them bad advice. 

Various media outlets are reporting the suit, filed in Colorado state court, requests unspecified damages for Eric and Ryan Jensen. The brothers have reached a plea agreement with the U.S. Attorney on the six charges they each face. They could be sentenced to up to six years each and fined up to $1.5 million each.

The third-party food safety audit done just before the Jensens began harvesting their cantaloupe in 2011 scored the fourth-generation Jensen Farms 96 out of 100 possible points.

Within weeks people were infected with listeria monocytogenes. At least 33 people died and more than 140 people across the nation were sickened with outbreak strains of listeria found in the Jensens packing facility and on cantaloupe in the packing facility.

An inspection by the Food and Drug Administration found that used potato packing equipment the Jensens were using was not appropriate for cantaloupe because it could not be easily cleaned. The FDA also found fault with the Jensens cooler.

Inspectors also theorized that a truck used to haul culled cantaloupes to a nearby cattle feeding operation transferred listeria from the cattle operation to its parking spot at the Jensens’ farm, where the pathogen was tracked into the packing facility on employees’ shoes.