Dylan McDermott Finds Truth Surrounding His Mother's Death

Dylan McDermott insisted that police re-open the investigation of his mother's death in 1967. Now, police have determined her death wasn't accidental, it was murder. INSIDE EDITION has the details.

Actor Dylan McDermott has helped solve a 45-year-old mystery surrounding his own mother's murder.

Cops say the star of The Practice and American Horror Story pushed them to re-open the investigation into how his mom died in 1967.

Dylan McDermott was only 5 years old when cops ruled his mom had accidentally shot herself. But McDermott never bought that theory. He thought she'd been murdered. So, not long ago, the actor asked cops to re-open the case, and now the state medical examiner has ruled the gun was actually pressed to the back of his mother's  head—making it a homicide—not an accident.  

Cops say the killer was John Sponza, McDermott's mom's boyfriend.

Sponza, an organized crime figure, was found slain himself in the trunk of a car in 1972.

Dylan McDermott was able to overcome his tragic childhood and become a star. He got his big break in the Clint Eastwood movie In the Line of Fire, playing a Secret Service agent.

Raised by his grandmother, he never forgot the circumstances of his mother's death. On CBS Sunday Morning, McDermott said, "We lived on $100 a week, my sister and I. And my grandmother worked two jobs."

McDermott just tweeted this about his 45-year fight to bring his mom justice: "I'd like to thank everyone for their amazing support today.  It means so much to me. It's been a long, hard journey that ended in victory."