Fourteen employees of a now-defunct Massachusetts compounding pharmacy were arrested Wednesday in connection to a 2012 meningitis outbreak that killed 64 people, the Boston-based U.S. attorney's office said.

Among those arrested were Gregory Conigliaro and Barry Cadden, who co-founded the New England Compounding Center in Framingham, Massachusetts. Conigliaro's relatives - Douglas and Carla Conigliaro - were also taken into custody at their homes during the mass arrest Wednesday before dawn, U.S. attorney's office spokeswoman Christina DiIorio Sterling said, according to The New York Times.

The heaviest charge on the 131-count indictment is second degree murder in seven states, which was brought against Cadden and the company's former head pharmacist, Glenn Adam Chin, who was arrested in September. Other charges include racketeering, of which Cadden and Chin are also charged, conspiracy and mail fraud, The NY Times reported. It was not immediately clear which defendant is charged with what crime.

Investigators allege that it was the contaminated drugs from the New England Compounding Center that sickened about 700 people with meningitis, a disease caused by the inflammation of the brain's and spinal cord's protective membranes, according to the Centers for Disease Control and Prevention.

Cases of the potentially fatal disease were reported in 20 states, with Tennessee, Indiana and Michigan seeing the most cases, CBS News reported. A total of 64 people died in the outbreak.

The outbreak was followed by a reevaluation of compounding pharmacies, which create customized drugs that cater to a patient's specific needs, according to the NY Times. The companies shipped their products all over the U.S. without much regulation from the federal government. New legislation to increase regulation has since been passed. 

The Conigliaro family and Cadden, who is married to Gregory's sister Lisa, founded the pharmacy in 1998 and became a national supplier of specialized drugs. After the outbreak, the company was bombarded with lawsuits from victims and their families and eventually filed for bankruptcy protection, CBS News reported.