The State Police said the 30 people arrested Tuesday morning face charges including racketeering, extortion, drug dealing and illegal firearms.
About two dozen people were arrested in November in the ongoing State Police investigation into organized crime.
Among those newly arrested is 53-year-old Terrell Walker of Boston. He served an 18- to 20-year prison sentence for manslaughter in the shooting death of police Detective John Schroeder.
Authorities said Walker was caught trying to arrange for a cocaine delivery. It was not immediately clear if he had a lawyer.