Massachusetts State Police say they've charged a prison guard with trafficking heroin after a weekslong investigation.

Police said 40-year-old Stephen Lebreux, of Swansea, was arrested Tuesday after police set up an undercover heroin purchase.

Lebreux is a corrections officer at the state prison in Bridgewater.

Police say an undercover officer made multiple heroin buys from Lebreux while he was off-duty and not at the prison.

Lebreux is being held at the state police barracks in Dartmouth and is scheduled to be arraigned Wednesday at Fall River District Court. No further details were immediately available.

It's unclear whether Lebreux is represented by an attorney.