By Sara Powers

(CNN) – What happened at the Abbott Nutrition Plant in Sturgis, Michigan?

That’s still the big question after the company recalled three popular brands of powdered infant formula back in February.

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Multiple babies got a rare and serious bacterial infection after eating formula made at the plant, and two babies died.

Now, there’s new information that a whistleblower complained to the FDA about safety concerns, months before the formula was taken off store shelves.

The complaint was sent in October and just released this week.

A former employee at the plant laid out concerns about poor cleaning practices, falsified records, and instances where employees knowingly put out formula that may have been contaminated.

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The complaint says the employee was fired for raising safety concerns — and he was one of a number of people who came forward about safety issues.

Abbott says it’s investigating and cooperating with the FDA’s investigation.

Though the FDA is under scrutiny for its handling of the case.

Having received this complaint in October but didn’t interview the former employee until December and didn’t do an in-person inspection of the Sturgis facility until January.

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