Dylan McDermott, the Irish American star of “American Horror Story,” has helped local police to track down his own mother’s killer.

The death of his mother Diane McDermott, in 1967, was ruled as an accident at the time. But McDermott, who was five years old at the time, was outside the house and witnessed events prior to the shooting.

Connecticut newspaper the Republican-American reported that over a year ago McDermott contacted the police with questions about the circumstances surrounding her death.

Having examined the case once more, police found they had enough evidence to charge McDermott 's mother’s boyfriend, John Sponza, whom McDermott had suspected all along.

Although McDermott declined to comment on the new findings in the case, with which he has always been obsessed, he did comment, “I'm happy to know my mother wasn't mentally ill or depressed.”

“Somebody took her from us; she didn't leave us," he said.

Sponza, who had connections to organized crime, was found dead in the parking lot of a Massachusetts grocery store in 1972.

At the time of Diane’s murder, Sponza had locked five-year-old McDermott outside the house.

Sponza told the police that Diane had picked up a gun he had been cleaning, and it went off.

During the reinvestigation, the state’s medical examiner concluded that the gun found near Diane’s body was too small a caliber to have been the weapon used in her murder.

The Republican-American also quoted the examiner saying that “the wound also showed that the murder weapon had been pressed to the back of her head.”

Speaking about the reinvestigation, Police Superintendent Michael Gugliotti said  it was worrying how little the police had looked into Sponza’s statement at the time. 

“Sponza is telling the police that night that he very rarely, if ever, had arguments, yet everyone we spoke to, including Dylan, who was only five at the time, remembered very violent, vicious arguments," Gugliotti said.

“Dylan vividly recalls the amount of times, not only flashing the gun, but pointing it at the kid, saying, ‘Shut up and get out of here.’ He’s still probably traumatized by that.”

Guiliotti and Mayor Neil M O’Leary met McDermott last year at a fundraiser.

According to Guliotti,  “[McDermott] said in order for me to survive and to get where I am today, I needed to bury that moment in my life deep within myself. He said it wasn't until recently that I've come to the point in my life where I'm able to begin to process all of this and make it part of his life.”

The Irish American actor’s curiosity about his mother’s death has led the police to reinvestigate at least two other unsolved murders.