A peanut plant in Blakely, Georgia, is now a crime scene after an outbreak of salmonella that may have killed eight people in the United States.
Some 529 people have been reported ill. More than half were children.
The plant operated by Peanut Corp of America is closed.
State and federal health officials say they have found widespread violations and contamination at the plant and evidence that plant management knowingly shipped products tainted with salmonella.
The US Food and Drug Administration and the Justice Department are investigating.
Earlier this week, Peanut Corp of America expanded a recall to include all products made at the plant since 1 January, 2007, beyond the original date of 1 July, 2008.
So far, the recall affects more than 400 products and a wide range of food manufacturers and retailers, including Kellogg Co and General Mills Inc.
Dr. Stephen Sundlof of the FDA said there is no evidence that major national peanut butter brands are contaminated.
Peanut butter from the plant was sold mostly to institutions including schools and long-term care facilities in large-size cans.