The salmonella strain linked to a nationwide outbreak has been found in irrigation water and in a sample from a batch of serrano peppers at a Mexican farm, federal health officials said Wednesday.
Dr. David Acheson, the Food and Drug Administration's food safety chief, called the finding a key breakthrough in the case.
"We have a smoking gun, it appears," said Dr. Lonnie King, who directs the center for foodborne illnesses at the U.S. Centers for Disease Control and Prevention.
Acheson said the farm is in Nuevo Leon, Mexico. Previously, the FDA had traced a contaminated jalapeno pepper to a farm in another part of Mexico, called Tamaulipas. Both farms shipped through a packing facility in Nuevo Leon, raising the possibility contamination could have occurred there.