THOMASTON – A Rockland man shot himself to death on U.S. Route 1 moments after repeatedly ramming his ex-girlfriend’s car and forcing it into a ditch.

Lucas G. Kostopoulous, 27, of Rockland was dead on arrival from a single gunshot wound after being taken to Penobscot Bay Medical Center in Rockport on Sunday evening.

Sgt. Mike Janczura of the Thomaston Police Department said Monday that Kostopoulous was traveling north following his ex-girlfriend’s Ford Contour in an older model Chevrolet Baretta when he suddenly began ramming into the other car.

He eventually managed to force the Ford off the road and into a ditch near the south entrance of Dragon Products.

Janczura said Kostopoulous pulled his vehicle alongside the ditched Ford and got out of his car wielding a 9 mm handgun.

When Kostopoulous apparently realized that the driver of the vehicle was not his ex-girlfriend but her 17-year-old sister, he put the gun to his head and pulled the trigger.

The girl was not injured. The gun was recovered at the scene.

“She yelled at him that she was not her sister and he turned the weapon on himself,” Janczura said Monday.

Janczura said police received the call at 5:30 p.m. and that a number of cars were parked along the road when he and Patrolman Michael Blais arrived.

Janczura said Route 1 was shut down for about three hours while police conducted their investigation. He said detectives from the Maine State Police Criminal Investigation Division assisted the department as did the Knox County Sheriff’s Department.