DOJ investigating conduct at Abbott infant formula plant

The Justice Department is investigating conduct at Abbott Laboratories' infant formula plant in Sturgis, Michigan, in connection with a contamination investigation that closed the plant last year, a source familiar with the matter told ABC News.

The monthslong shutdown of the plant amid a investigation helped trigger a nationwide formula shortage.

An Abbott spokesperson told ABC News, "DOJ has informed us of its investigation and we're cooperating fully."

The DOJ did not immediately respond to a request for comment.

The Consumer Protection branch of the DOJ is conducting the criminal investigation, the source familiar said.

The discovery of Cronobacter sakazakii bacteria inside Abbott's Sturgis plant prompted a massive voluntary formula recall in February, after four babies who had consumed Abbott's formula contracted a Cronobacter infection.

Two of the infants subsequently died, although Abbott maintains there has not been conclusive evidence that its formula caused the infant illnesses, since none of the Cronobacter strains found at their plant matched the two samples genetically sequenced from the sickened infants.

Food and Drug Administration officials said the investigation remains ongoing.

Ultimately, it was the combined findings of Cronobacter inside Abbott's plant -- along with a pattern of serious operational deficiencies and consumer complaints -- which led to the plant's closure.

The plant reopened in June and restarted production of its largest formula Similac in August.