(CNN) -- Michigan and federal authorities will coordinate their criminal investigations into a deadly fungal meningitis outbreak that killed 22 people in that state and 64 people total nationwide, the Michigan attorney general and the U.S. attorney for Massachusetts said Monday in Detroit.
However, Michigan -- which had the most deaths of any single state in the 2012 outbreak -- will let its own grand jury in the case take a "temporary pause" in the probe of the Massachusetts-based New England Compounding Center, Michigan Attorney General Bill Schuette said.
The Michigan grand jury hasn't announced any indictments and its six-month term is set to expire soon, though a judge could call it back, Schuette said. He emphasized his agreement with the U.S. attorney for Massachusetts, Carmen Ortiz, saying it will ensure state investigators see the evidence that a federal grand jury in Boston is seeing, and vice versa.
"This will help us reach our mutual goal: to secure justice for victims of fungal meningitis," Schuette said. "... By working together we can ensure our investigative efforts are not duplicated."
The outbreak, thought to be caused by tainted steroid injections from the New England Compounding Center, infected 751 people in 20 states last year, the Centers for Disease Control and Prevention reported. More than 260 of the infected were Michigan citizens, Schuette said.
The company filed for bankruptcy last December. A state pharmacy board also voted to permanently revoke the company's license to operate as well as the licenses of the company's three principal pharmacists.
No one has yet been charged in the case, said Ortiz, who appeared with Schuette at a news conference in Detroit Monday morning.
She declined to discuss details of the investigation, but said she is confident in the direction it is going.
Symptoms of fungal meningitis can include headache, fever, nausea, stiff neck, new weakness or numbness anywhere in the body, slurred speech, pain or swelling at the injection site and sensitivity to light, according to the CDC.
Compounding pharmacists customize medications to fit an individual's needs. Doctors prescribe these custom medications when the manufactured drug won't work -- for example, when a dosage is too large, or a patient has an allergy to a dye or ingredient in the commonly available product.