Three people face drug trafficking charges following a Maine Drug Enforcement Agency investigation in Knox, Lincoln and Kennebec counties.

Agents on Tuesday arrested James Millay, 42, and Jody Daniello, 35, both of Thomaston, and Donna Johnson, 42, of China.

The MDEA spent three months investigating heroin trafficking in the midcoast region. Police said Millay and Daniello would travel each week to China to buy heroin from Johnson and others, then resell it in Knox and Lincoln counties.

Maine State Police stopped the car Millay and Johnson were riding in on Route 17 on Tuesday night in Jefferson. Police seized 20 grams of heroin in the car. They later raided Johnson’s home on Fire Road 31 and seized another 39 grams of heroin, a .38-caliber handgun and $5,000 in suspected drug proceeds.

The three were taken to Two Bridges Regional Jail in Wiscasset and are being held on $10,000 bail pending a Feb. 25 court date.

The MDEA worked with the Lincoln County and Knox County sheriffs’ offices and the state police.