The co-founder of a specialty pharmacy that was at the center of a deadly national meningitis outbreak in 2012 pleaded no contest to involuntary manslaughter in Michigan, authorities said Tuesday.

Under a deal, Barry Cadden’s prison sentence of 10 to 15 years will be served at the same time as his current 14 1/2-year federal sentence for fraud and other crimes, Attorney General Dana Nessel said.

Cadden was co-founder of New England Compounding Center in Massachusetts, which specialized in making drugs for certain treatments and supplying them to doctors across the U.S.

About 800 patients in 20 states were sickened with fungal meningitis or other infections, and about 100 died, after receiving injections of mold-tainted steroids, mostly for back pain, investigators said.

Cadden appeared Monday in Livingston County court, 65 miles (105 kilometers) northwest of Detroit. He pleaded no contest to 11 counts of involuntary manslaughter, one charge each for the number of people in Michigan who died, Nessel said.

Cadden had been awaiting trial on second-degree murder charges before the plea deal. A no-contest plea is treated the same as a guilty plea for sentencing purposes. He will return to court on April 18.

“Patients must be able to trust their medications are safe, and doctors must be assured they aren’t administering deadly poison,” Nessel said.

Cadden’s attorney, Gerald Gleeson II, declined to comment Tuesday.

In federal court in Boston in 2017, Cadden said: “I am sorry for the whole range of suffering that resulted from my company’s drugs.”

Prosecutors in Boston said the lab cut corners to boost profits, neglected to properly disinfect its rooms, shipped drugs before receiving test results and ignored warnings that its methods were unsafe.

Another Michigan criminal case is pending against pharmacist Glenn Chin, records show. His next court hearing is scheduled for March 15.

Cadden and Chin were charged in Michigan in 2018, though their cases moved slowly because of separate federal prosecutions, appeals and other issues.