The Agriculture Department officials have said that the contaminated iceberg lettuce, which sickened 36 people with E-coli in Michigan, grew in California. According to the Michigan Department of Community Health, it is most likely that the industrial size packages of iceberg lettuce sold to restaurants and institutions spread the E coli in Michigan State University and Lenawee County Jail in early September, before spreading to metro Detroit.

Jennifer Holton, a spokeswoman for the Michigan Department of Agriculture said, "Illness dates, ship dates and delivery dates narrow the origin to California."

One of the local suppliers was identified as Aunt Mid's Produce of Detroit. Philip Riggio, chief executive officer said the company had immediately stopped lettuce distribution and had its supply and processing facilities tested by outside experts who found no evidence of contamination.

Aunt Mid's lettuce was tested by the Michigan Department of Agriculture, with no findings of E. coli, but, "we never had product available that was tested from the outbreak timeframe, primarily due to the perishable nature of the product we dealt with," said Holton. Aunt Mid's will be able to resume operations soon she said.

Saying the outbreak may be over, health department spokesman James McCurtis said, "I'm sure the bad lettuce is no longer on the market, because we'd be seeing cases from a new onset date."

Ken August, a spokesman with the California agency said the source of the contamination was still unknown and the California Department of Public Health is working with the U.S. Food and Drug Administration and the state of Michigan.