Three people have been charged with distributing heroin in Kennebec, Knox and Lincoln counties after a month-long investigation.

Donna Johnson, 42, of China, is charged with conspiracy to traffic in heroin.

Jody Daniello, 35, of Thomaston, is charged with trafficking in heroin. James Millay, 42, also of Thomaston, is charged with aggravated trafficking in heroin.

The investigation was conducted by the Maine Drug Enforcement Agency as well as Maine State Police and sheriff’s deputies in Knox and Lincoln counties.

All three were arrested Tuesday night and are being held at the Two Bridges Regional Jail in Wiscasset in lieu of $10,000 cash bail each.

Steve McCausland, spokesman for the Maine Department of Public Safety, said all three were arrested after an investigation revealed Millay and Daniello made weekly trips from Thomaston to China to buy heroin from Johnson and others. Millay and Daniello then resold the heroin throughout Knox and Lincoln counties.

Drug agents and Maine State Police stopped Millay and Daniello’s vehicle Tuesday night on Route 17 in Jefferson, McCausland said. Police found 20 grams of heroin in the vehicle. The heroin is equal to about 200 doses.

McCausland said drug agents later searched Johnson’s home on Fire Road 31 on China Lake and found 39 grams of heroin, which is about 390 doses. McCausland said police also found a loaded .38-caliber handgun and $5,000, which investigators suspect represents the proceeds of drug sales.

McCausland said the estimated street value of the seized heroin is $18,000. The investigation is ongoing, and additional arrests are expected.

McCausland asked anyone with information about the illegal sale of drugs to call the MDEA tip line at 800-452-6457.