The Maine Drug Enforcement Agency said four people face drug charges after a heroin-prescription drug distribution ring was broken up in Knox County, according to a news release from the Maine Department of Public Safety.

The four arrested are Michel Dangelo, 31, of Acton and Waldoboro for trafficking oxycodone; Aaron Dennison, 24, of South Thomaston for trafficking oxycodone; Mathew Catalano, 28, of Rockland for trafficking heroin; and Justin Myrick, 22, of Owls Head for trafficking oxycodone.

James Pease, supervisor of the MDEA’s Mid-Coast District Task Force Office, said drug agents, Rockland police, Knox County Sheriff’s Office deputies and state police have been looking into the importation of heroin and oxycodone, a prescription narcotic, into the Rockland area during the four-month investigation.

According to the news release, the investigation focused on Dangelo being suspected of smuggling quantities of heroin and oxycodone 30 milligram pills from Massachusetts into Knox County. Several individuals then distributed the drugs in the county, according to the Department of Public Safety. During surveillance, agents reportedly observed that most of the transactions were taking place in public parking lots around Rockland. Agents reportedly made undercover purchases from several people.

On May 13, agents arrested Dennison at his South Thomaston residence and Catalano at his Rockland residence with the assistance of the Knox County Sheriff’s Office and Rockland police.

On May 25, agents arrested Dangelo at the Rockland Superior Courthouse with the assistance of Rockland police.

On May 31, agents arrested Myrick during a traffic stop with the assistance of Maine State Police.

The investigation continues with additional charges anticipated, according to the Department of Public Safety. The four were taken to the Knox County Jail and are now free on bail.