United States Attorney Nicola T. Hanna, the chief federal law enforcement officer for the Central District of California and the Food and Drug Administration ‘s Office of Criminal Investigations (OCI)  are continuing a criminal investigation of Chipotle Mexican Grill that dates back to 2015.

That was when a string of back-to-back outbreaks that plagued Chipotle at locations throughout the country. During the last half of 2015, Chipotle experienced misfortune for its business and saw it’s stock value hammered. Those incidents included:

• Seattle — E. coli O157:H7, July 2015, five sickened people, source unknown;
• Simi Valley, CA — Norovirus, August 2015, 234 people, the source was a sick employee;
• Minnesota — Salmonella Newport, August and September 2015, 64 sick people, the source was tomatoes but it is not known at what point in the field-to-fork chain the pathogen was introduced;
• Nine states — E. coli O26, began October 2015 and declared over on Feb. 1, 55 sickened people, source unknown, states involved are California, Delaware, Illinois, Kentucky, Maryland, Minnesota, New York, Ohio, Oregon, Pennsylvania and Washington, and,
• Three states — E. coli O26, began December 2015, declared over Feb. 1, five sickened people, source unknown, states involved are Kansas, Oklahoma, and Nebraska.
• Boston — Norovirus, December 2015, 151 sickened.

In Chipotle’s latest Securities Exchange Act filing, the fast-casual restaurant chain reports receiving a new subpoena on April 18 in conjunction with the criminal investigation.

According to the filing, the subpoena was “requesting information related to illness incidents associated with the specific restaurants in Simi Valley, California, Boston, Massachusetts, Sterling, Virginia, and Los Angeles, California covered under the previous subpoenas, plus one additional restaurant in Powell, Ohio.

An outbreak of Clostridium perfringens reportedly sickened 647 diners associated with Chipotle’s Powell, Ohio unit.

Chipolte was first served with a Federal Grand Jury Subpoena from the U.S. District Court for the Central District of California on Jan. 28, 2016.

“The subpoena required the production of documents and information related to company-wide food safety matters dating back to January 1, 2013,” the Securities Exchange Act filing said. “Since then we have received two other subpoenas on the following dates requesting information related to illness incidents associated with the following specific restaurants: July 19, 2017, requesting information about a single Chipotle restaurant in Sterling, Virginia; and February 14, 2018, requesting information about a single Chipotle restaurant in Los Angeles, California.”

Thus the latest subpoena is the fourth received by Chipotle in the criminal matter that has been going on for more than three years.

“We have fully cooperated and intend to continue to fully cooperate in the investigation. It is not possible at this time to determine whether we will incur, or to reasonably estimate the amount of, any fines or penalties in connection with the investigation pursuant to which the subpoenas were issued,” according to the notice intended for stockholders.

The disclosure of another subpoena came one day after Chipotle reported positive first quarter results with the Securities and Exchange Commission (SEC).

Revenue for the quarter was $1.3 billion, an increase of 13.9 percent from the first quarter of 2018. It opened 15 new restaurants during the period and closed two for a total restaurant count of 2,504. The chain recently moved its headquarters to Newport Beach, CA, from Denver wher its first restaurant was located.

Chipotle stock (CMG) during April has traded at levels not seen since before its 2015 outbreaks.