More than 30 individuals have been arrested on drug charges after a large, undercover investigation exposed a heroin and fentanyl distribution ring operating in parts of Middlesex County, according to Attorney General Maura Healey’s office.

The investigation, which involved Healey’s office, the State Police Gang Unit, and the Marlborough Police Department, was launched in response to an increase of opioid overdoses in the area, prosecutors said in a statement.

“As the state of Massachusetts and the entire country continue to grapple with the heroin epidemic, law enforcement wants to send a strong message that dealing deadly opiates will not be tolerated and serious consequences can result,” Marlborough Police Chief David Giorgi said in the statement.


The drug ring operated in Marlborough, Hudson, and surrounding communities, prosecutors said. Dealers worked in local parks, restaurants, and other public places until authorities were able to arrest 28 individuals Monday in connection to drug sales made to an undercover officer.

Three others were arrested and arraigned in Marlborough District Court in May and June as part of the investigation, prosecutors said.

All but one of the 28 individuals arrested Monday were arraigned Monday and Tuesday in Marlborough District Court, prosecutors said. One defaulted on his arraignment in Westborough District Court on Tuesday.

“Through the extensive efforts of this joint investigation, we were able to dismantle a major heroin and fentanyl distribution ring that brought these deadly drugs into several local communities,” Healey said in the statement.

Alyssa Meyers can be reached at alyssa.meyers@globe.com. Follow her on Twitter @ameyers_.