A congressional committee's investigation blamed Jensen Farms and private auditors Primus Labs and Bio Food Safety in the outbreak that led to 30 deaths nationwide, The Denver Post reported Wednesday.
The committee's report said problems are inevitable when a food company hires private auditors while seeking high marks.
Jensen and its distributor Frontera Produce had ample prior notice of the private auditors' visits and discussed how to handle them, the report said.
Auditors ended up giving Jensen Farms a 96 percent positive score just before contaminated melons were shipped.
Critics of current food-safety regulation cite the report as proof the government needs to increase inspections and testing instead of relying on the food industry to police itself while hiring third-party auditors to give a biased seal of approval.
"The take-home of this is they are not a substitute for government inspection. They don't do the same things, they don't produce the same results, and they don't lead to food safety," Amanda Hitt of the Food Integrity Campaign in Washington, D.C., said.