Qdoba Chipotle 10

Chipotle has been subpoenaed as part of a federal criminal investigation into food safety at its restaurants nationwide.

The subpoena broadens the scope of a previously announced investigation, which focused on a norovirus outbreak at a Chipotle restaurant in California.

The investigation is being conducted by the US attorney's office for the Central District of California and the US Food and Drug Administration's Office of Criminal Investigations.

Chipotle said in a press release:

The new subpoena requires us to produce documents and information related to company-wide food safety matters dating back to January 1, 2013, and supersedes the subpoena served in December 2015 that was limited to a single Chipotle restaurant in Simi Valley, California. We intend to fully cooperate in the investigation.

The subpoena means that prosecutors are gathering evidence to present to a grand jury, which will decide whether to make an indictment. The charges have not been specified. We reached out to the FDA for more information and will update this post when we hear back.

Criminal investigations into outbreaks of foodborne illnesses are uncommon, according to Dr. William Schaffner, an infectious-diseases specialist at Vanderbilt University Medical Center.

"Deliberately instigated foodborne illnesses are not unknown, but boy are they rare," Schaffner told Business Insider.

A man snaps a photograph at the entrance to Chipotle Mexican Grill in San Francisco, California July 21, 2015. REUTERS/Robert Galbraith

The norovirus outbreak linked to the Simi Valley Chipotle restaurant sickened about 230 customers in August, according to public records obtained by Food Safety News.

Health inspectors visited the restaurant after the illnesses were reported and cited the company for violations in pest control, sanitation, and maintenance, according to the documents.

Inspectors also found that the restaurant was holding food at unsafe temperatures of below 135 degrees Fahrenheit, Food Safety News reported.

Norovirus is highly contagious and causes symptoms like stomach aches, nausea, diarrhea, and vomiting. It's the most common cause of foodborne illness in the US, with more than 21 million cases annually.

Story continues

In addition to the norovirus outbreak, Chipotle has also been identified as the source of two E. coli outbreaks and another norovirus outbreak in Boston that have sickened more than 200 people over the past several months.

The first reports of E. coli sickening Chipotle customers were revealed in October. Three months and thousands of tests later, health investigators still can't find the source of the outbreaks.

That's unusual, according to several food-contamination experts. In five similar high-profile cases of major foodborne-illness outbreaks over the last couple of decades, the source of the outbreaks was determined relatively quickly, according to a Credit Suisse analysis.

chipotle burrito

On top of investigations by state and local health officials, Chipotle has done hundreds of internal tests on its food and surfaces without finding a trace of E. coli.

The mystery surrounding Chipotle's outbreak has sparked some conspiracy theories, including one that claims that Chipotle's competitors planted E. coli in the company's food.

But the US Centers for Disease Control and Prevention says that not being able to pinpoint to cause of a foodborne-illness outbreak isn't all that uncommon.

Tom Skinner, a CDC spokesman, told Business Insider in a previous interview:

When a food is identified as the source of an outbreak, up to 50% of the time a specific food item is not pinpointed as the cause. What is making this particular outbreak difficult to pinpoint is you have lots of different food items that are going into the product that consumers are buying.

The CDC declared the end to the Chipotle E. coli outbreaks on Monday, but the chain will likely be feeling the effects for at least the next year.

The company reported on Tuesday that its same-store sales fell 14.6% in the fourth quarter, and net income fell 44%. Credit Suisse is predicting an overall comp-sales decline of 7.4% for 2016.

NOW WATCH: A criminal investigation is underway at Chipotle





More From Business Insider

