Chipotle Subpoenaed in Criminal Investigation tied to a Norovirus Case in California

The widely popular Mexican chain restaurant, Chipotle Mexican Grill Inc., continues to suffer blows to its business.

The company, based in Denver, Colorado, revealed that it was subpoenaed in relation to a criminal investigation into an isolated case of norovirus at a Chipotle location in Simi Valley, California. The subpoena, which Chipotle received in December, requires the company to hand over a "broad range of documents" for the Simi Valley location, the Los Angeles Times reported.

Chipotle spokesman Chris Arnold stated that they cannot comment on the case, which is being carried out by the U.S. Attorney's office for the Central District of California and the Food and Drug Administration's (FDA) Office of Criminal Investigation. The company did say that it would be fully cooperating with the investigators.

The investigation is just one of many problems that the company has had to deal with. Toward the end of last year, Chipotle was tied to an E. coli outbreak that sickened 53 people across nine states. The source of that outbreak is still unknown. In a separate incident, a Chipotle location in Boston was linked to a norovirus outbreak that caused more than 100 students to fall ill. The location has since been reopened.

Overall, Food Safety News reported that in the second half of 2015, more than 500 people got sick from eating at a Chipotle.

Since these outbreaks, Chipotle sales have plummeted. The company revealed Wednesday that fourth quarter sales at established locations fell by 14.6 percent. In December, specifically, sales dropped by 30 percent.

The outbreaks have also forced Chipotle to change how they source and prepare their produce.