(Dec. 13, 5:55 pm CST) According to a late breaking Associated Press report today, the E. coli 0157:H7 outbreak tied to various Taco Bell restaurants on the East Coast may have been caused by tainted lettuce, and not by green onions as originally believed.

The report noted that federal health officials determined lettuce could be the smoking gun in the case since lettuce was the item that those sickened in the outbreak most commonly reported eating.

The article said that investigators arrived at the determination through interviews with hospitalized patients and through other work.

Nonetheless, officials are apparently also looking into the roles that cheddar cheese and ground beef could have played in the outbreak. The probe has been complicated, the AP explained, by the fact that many Taco Bell menu items contain a combination of multiple ingredients -- any one of which could have carried the E. coli.

Thus far, there have been a reported 71 cases of E. coli in the Taco Bell matter, mainly in New Jersey, New York and Pennsylvania. Green onions were initially implicated in the outbreak, but later government testing indicated the commodity may not have been to blame after all.

Taco Bell issued a news release Dec. 11 saying that there have been no new illnesses from the outbreak since Dec. 2.

Despite the uncertainty about which food(s) caused the illnesses, the company said it has replaced its former produce supplier for New York, New Jersey, Pennsylvania and Delaware Taco Bells. Those locations will now be served by Salinas, Calif.-based Taylor Farms.