ALBANY, Ga. — A ConAgra subsidiary pleaded guilty Tuesday and agreed to pay $11.2 million – including the largest criminal fine ever imposed for a foodborne illness in the United States – to resolve a decade-long criminal investigation into a nationwide salmonella outbreak blamed on tainted peanut butter.

ConAgra admitted to a single misdemeanor count of shipping adulterated food. No individuals at the leading food conglomerate faced any charges in the 2006 outbreak, which sickened at least 625 people in 47 states.

Disease detectives traced the salmonella to a plant in rural Sylvester, Georgia, that produced peanut butter for ConAgra under the Peter Pan label and the Great Value brand sold at Wal-Mart. In 2007 the company recalled all the peanut butter it had sold since 2004.

Leo Knowles, president of ConAgra Grocery Products, offered no testimony as he entered the misdemeanor plea Tuesday on behalf of the Chicago-based corporation’s subsidiary.

“It made a lot of people sick,” federal prosecutor Graham Thorpe said Tuesday as he described ConAgra’s decision to continue shipments from the Georgia plant in late 2006, before corrective actions were completed, despite lab tests that had twice detected salmonella in samples.

“The industry has taken notice of this prosecution,” Thorpe added.

Though the Justice Department called $8 million the heftiest criminal fine ever imposed in a U.S. food safety case, it represents just one-tenth of 1 percent of ConAgra’s current $8 billion market capitalization. The company also will pay $3.2 million in cash forfeitures to the federal government.

U.S. District Court Judge W. Louis Sands waited more than 18 months after ConAgra agreed to the plea deal with prosecutors, so that victims could be contacted before he approved the settlement.

The case began in 2006, as doctors around the country reported severe gastrointestinal illnesses caused by salmonella. The Centers for Disease Control and state health officials traced the common factor – peanut butter – to the plant in rural Georgia.

Despite the widespread illnesses, no deaths were ever confirmed to be caused by the salmonella outbreak.