A reopened police investigation has concluded that actor Dylan McDermott's mother was killed in 1967 by her now-dead gangster boyfriend.

Waterbury police reopened the investigation last year into Diane McDermott's death after Dylan McDermott contacted them with questions, the Republican-American newspaper reported Sunday and Monday as part of a two-part series.

He was 5 years old when his mother was shot in February 1967. Her death was originally ruled an accident.

Police told the newspaper that the evidence they found would be enough to file murder charges against John Sponza, who lived with McDermott at the time. He had told authorities that McDermott accidentally shot herself after picking up a gun he had been cleaning.

Sponza, who police say had ties to organized crime, was shot to death in 1972, his body found in the trunk of a car in a Waltham, Mass., grocery store parking lot.

H. Wayne Carver, the state's medical examiner, reviewed McDermott's autopsy and determined that the gun found near the body was too small a caliber to have been the weapon used to kill her.