Two men were arrested in Colorado in connection with a listeria outbreak that killed 33 people in 2011.

Brothers Eric and Ryan Jensen have been charged with introducing adulterated food into interstate commerce. (Adulterated food is any food that is impure, unsafe or unwholesome.)

The Food and Drug Administration and the Centers for Disease Control told prosecutors that the farm owned by the men did not adequately clean cantaloupe that was contaminated by the bacteria. The FDA said melons were in contact with dirty water on a packing house floor and that old, hard-to-clean equipment also contributed to the contamination.

The outbreak was called the deadliest foodborne illness outbreak in 25 years. The Jensen brothers filed for bankruptcy after the outbreak. A number of lawsuits are pending against the farm and family.