Already more than 400 kinds of cakes, cookies and other goods have been pulled off the shelves in one of the largest product recalls.
At the center of the investigation is a Georgia peanut processing plant where federal inspectors reported finding roaches, mold, a leaking roof and other sanitary problems.
Managers at the Blakely, Ga., plant owned by Peanut Corp. of America continued shipping peanut products even after they were found to contain salmonella.
Peanut Corp. expanded its recall Wednesday to all peanut products produced at the plant since Jan. 1, 2007. The company is relatively small, but its peanut paste is an ingredient in hundreds of food products, from ice cream, to Asian-style sauces, to dog biscuits.
A senior lawmaker in Congress and Georgia's agriculture commissioner called for a criminal investigation of the company, but the Food and Drug Administration said such a step is premature while its own food safety investigation continues.
More than 500 people have gotten sick in the outbreak and at least eight may have died as a result of salmonella infection. The plant has stopped all production.
"We feel very confident that it's one of the largest recalls we've had," said Stephen Sundlof, head of the FDA's food safety center. "We're still in the process of identifying products, but it certainly is among the largest."
Most of the older products recalled Wednesday have probably been eaten already. Officials said they see no signs of any earlier outbreaks that might be linked to the plant.
The latest recall covers peanut butter, peanut paste, peanut meal and granulated products, as well as all peanuts - dry and oil roasted - shipped from the factory. FDA officials could not quantify the amount of products being recalled. Major national brands of peanut butter are not affected.
Late Wednesday, Peanut Corp. of America President Stewart Parnell released a statement saying the recall was expanded out of an abundance of caution.
"We have been devastated by this, and we have been working around the clock with the FDA to ensure any potentially unsafe products are removed from the market immediately," Parnell said, adding that company officials are cooperating with state and federal inquiries.
Salmonella had been found previously at least 12 times in products made at the plant, but production lines were never cleaned after internal tests indicated contamination, FDA inspectors said in a report. Products that initially tested positive were retested. When the company got a negative reading, it shipped the products out.
That happened as recently as September. A month later, health officials started picking up signals of the salmonella outbreak.
PCA on Wednesday said it "categorically denies any allegations that the company sought favorable results from any lab in order to ship its products."
Michael Rogers, a senior FDA investigator, said it's possible for salmonella to hide in small pockets of a large batch of peanut butter. That means the same batch can yield both positive and negative results, he said. The products should have been discarded after they first tested positive.
Separately, senior congressional and state officials on Wednesday called for a federal probe of possible criminal violations at the plant.
The company's actions "can only be described as reprehensible and criminal," said Rep. Rosa DeLauro, D-Conn., who oversees FDA funding. "This behavior represents the worst of our current food safety regulatory system."
In Georgia, the state's top agriculture official joined DeLauro in asking the Justice Department to determine whether the case warrants criminal prosecution.