Linda MaxwellMaine State Police

A Bangor, Maine man has been arrested for the killing of an 18-year-old girl who went missing in 1984 and later washed up on the shore of the St. Croix River, authorities said Thursday.

Raymond Brown, 65, was arrested during a traffic stop at about 4:15 p.m., according to Maine State Police.

The murder of Linda Maxwell had gone unsolved for more than 40 years.

Maxwell lived in Calais and was last seen in the area on a Thursday night, Aug. 23, 1984, while she was hanging out with friends, a spokesperson for Maine State Police said.

Two days later, and 12 miles away, Maxwell’s unclothed body washed ashore on the St. Croix River near the RobbinstonBoat Landing, authorities said.

Despite an intensive and expansive investigation, an arrest was never made — until Thursday.

Law enforcement officials did not specify how Brown became a suspect.

Detectives who oversee major crimes and unsolved cases worked with the Maine attorney general’s office, which presented the case to a grand jury in Washington County.

The grand jury later handed up the murder indictment, state police said.

“This arrest reflects the continued commitment of the Maine State Police and the Attorney General’s Office to pursue justice in homicide cases, regardless of how much time has passed,” a Maine State Police spokesperson said.

Brown is being held without bail at the Washington County Jail.

Tonya Alanez can be reached at tonya.alanez@globe.com. Follow her @talanez.