WATERBURY, Conn. — 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. http://bit.ly/KX4WBx

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 accidently 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.

The state's medical examiner, H. Wayne Carver, 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. The wound also showed that the murder weapon had been pressed to the back of her head, according to his report.

Police Superintendent Michael Gugliotti also stumbled over some of the initial findings.

"What troubled me was that there was very little follow up other than the statement Sponza had given to police," Gugliotti said.

"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 5 at the time, remembered very violent, vicious arguments," he added. "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."

Dylan McDermott, who won a Golden Globe in 1999 for his role on the TV drama "The Practice," declined to comment to the newspaper about the investigation. His sister, Robin Herrera, said she is relieved that the truth has been discovered.

"I'm happy to know my mother wasn't mentally ill or depressed," she said. "Somebody took her from us; she didn't leave us."

Dylan McDermott met with Gugliotti and Mayor Neil M. O'Leary last year while in town for a fundraiser.

"He 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," Gugliotti said. "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."

Police said the McDermott investigation has led to evidence that also implicates Sponza in at least two other unsolved homicides.

___

Information from: Republican-American, http://www.rep-am.com

Also on HuffPost:

Loading Slideshow...
  • Celebrity Photos: April 2014

    Khloe Kardashian did some shopping with her mother Kris in West Hollywood on April 24.

  • Celebrity Photos: April 2014

    Newlywed Jodie Foster grabbed a smoothie in LA on April 24.

  • Celebrity Photos: April 2014

    Emma Stone stopped by the "Good Morning America" studios in NYC on April 24, with her "The Amazing Spider-Man 2" co-stars Andrew Garfield and Jamie Foxx.

  • Celebrity Photos: April 2014

    Tori Spelling's husband Dean McDermott had a heated exchange with a paparazzo in LA on April 23

  • Celebrity Photos: April 2014

    Jessica Alba landed in NYC on April 23.

  • Celebrity Photos: April 2014

    Rumer Willis attended the 5th Annual Elle Women in Music Celebration presented by CUSP by Neiman Marcus in Hollywood, Calif. Hosted by Elle Editor-in-Chief Robbie Myers, the April 22 event featured performances by Sarah McLachlan, Angel Haze and Betty Who.

  • Celebrity Photos: April 2014

    Eddie Murphy's daughters Shayne (left) and Bria Murphy attended Elle's 5th Annual Women in Music concert celebration on April 22 in Hollywood.

  • Celebrity Photos: April 2014

    Jason Sudeikis shared a laugh with Rebecca Hall on set of "Tumbledown" in Boston on April 22.

  • Celebrity Photos: April 2014

    Taylor Swift engaged in some retail therapy in NYC on April 22.

  • Celebrity News: April 2014

    Drew Barrymore gave birth to her second child, a baby girl named Frankie Barrymore Kopelman, on April 22.

  • Celebrity Photos: April 2014

    Cameron Diaz attended the premiere of "The Other Woman" at the Regency Village Theatre in Westwood, Calif., on April 21

  • Celebrity Photos: April 2014

    Katy Perry headed to Jimmy Kimmel's studio in Hollywood, Calif., on April 21.

  • Celebrity Photos: April 2014

    Sofia Vergara wowed at "Good Morning America" on April 21.

  • Celebrity Photos: April 2014

    Selena Gomez went on a coffee run in Studio City, Calif. on April 21.

  • Celebrity Photos: April 2014

    Busy Philipps and husband Marc Silverstein had some fun at Coachella on April 20.

  • Celebrity Photos: April 2014

    Gwen Stefani headed to her parents' house on Easter Sunday, April 20, with her husband Gavin Rossdale and three kids, Kingston, Zuma and Apollo.

  • Celebrity Photos: April 2014

    Tia Mowry soaked up some sun in Cabo, Mexico with her husband Cory Hardrict on April 19.

  • Celebrity Photos: April 2014

    Jennifer Lopez and boyfriend Casper Smart had a casual dinner at Madeo in West Hollywood on April 17.

  • Celebrity Photos: April 2014

    Aubrey Plaza, Jason Ritter, Dade Constantine, and Kayla Dobson attended the "About Alex" premiere afterparty during the Tribeca Film Festival at Kutsher's Tribeca in NYC, April 17.

  • Celebrity Photos: April 2014

    Pregnant singer Christina Aguilera and her fiance Matthew Rutler were photographed out and about in New York City on April 17.

  • Celebrity Photos: April 2014

    Katie Holmes spotted out and about in New York City on April 17.

  • Celebrity Photos: April 2014

    "Downton Abbey" actress Jessica Brown Findlay hopped on a train at Manchester Piccadilly Train Station after her interview on "BBC Breakfast" on April 17 in England.

  • Celebrity Photos: April 2014

    Heather Graham visited NBC Studios for an appearance on "The Today Show" on April 17 in New York City.

  • Celebrity Photos: April 2014

    Justin Bieber and his crew, including Lil Za, were spotted out for dinner at The Grove in Los Angeles, Calif., on April 16.

  • Celebrity Photos: April 2014

    Georgia May Jagger, daughter of Mick Jagger, filmed a commercial for Rimmel London in London, England, on April 15.

  • Celebrity Photos: April 2014

    Halle Berry filmed scenes for her TV series "Extant" in Century City, Calif. on April 15.

  • Celebrity Photos: April 2014

    Lauren Conrad did some shopping in West Hollywood on April 15.

  • Celebrity Photos: April 2014

    Andrew Garfield, Emma Stone, Jamie Foxx and Dane DeHaan posed during a photocall for their film "The Amazing Spider-Man 2" prior to the German premiere of the film in Berlin on April 15.

  • Celebrity Photos: April 2014

    Kim Kardashian and her fiance Kanye West walked hand-in-hand as they went shopping in Givenchy, Balmain and Lanvin on April 14 in Paris, France.

  • Celebrity Photos: April 2014

    Channing Tatum and Jenna Dewan-Tatum joked around backstage at the 2014 MTV Movie Awards at Nokia Theatre L.A. Live in Los Angeles, Calif., on April 13.

  • Celebrity Photos: April 2014

    Lupita Nyong'o arrived at the 2014 MTV Movie Awards at Nokia Theatre L.A. Live in Los Angeles, Calif., on April 13.

  • Celebrity Photos: April 2014

    Taylor Swift and a friend were spotted out and about in New York City on April 12.

  • Celebrity Photos: April 2014

    Jessica Biel was all smiles as she headed out for an espresso in New York City on April 12.

  • Celebrity Photos: April 2014

    Leonardo DiCaprio stopped by the McDonald’s® and Stingray Desert Coachella Pool Party at the Bootsy Bellows Estate on April 12 to celebrate the launch of McDonald’s® Bacon Clubhouse Burger™ and the 2014 Corvette Stingray.

  • Celebrity Photos: April 2014

    Julianne Hough looked Coachella cool at The Old Navy Oasis in Indio, Calif.m on April 12.

  • Celebrity Photos: April 2014

    Selena Gomez and Kendall and Kylie Jenner at the first weekend of The Coachella Valley Music and Arts Festival on April 11.

  • Celebrity Photos: April 2014

    Emma Stone and Andrew Garfield visited BBC Radio 1 in London on April 9 to promote their new film, "The Amazing Spider-Man 2."

  • Celebrity Photos: April 2014

    Pregnant Kristin Cavallari was spotted running in West Hollywood on April 9.

  • Celebrity Photos: April 2014

    Danica McKellar left "Dancing with the Stars" practice in Hollywood on April 8.

  • Celebrity Photos: April 2014

    Julianne Moore was pretty in white while out in NYC April 8.

  • Celebrity Photos: April 2014

    Anne Hathaway wrapped herself up in a giant coat while out in NYC on April 8.

  • Celebrity Photos: April 2014

    Lady Gaga struck her usual unique pose outside the Roseland Ballroom on April 7.

  • Celebrity News: April 2014

    British socialite <a href="http://www.huffingtonpost.com/2014/04/07/peaches-geldof-dead_n_5105968.html" target="_blank">Peaches Geldof died</a> of an "unexplained and sudden" cause on April 7. She was 25.

  • Celebrity Photos: April 7

    "Dancing with the Stars" star Derek Hough took a break from rehearsal on April 7 to snack on the new Ritz crackers.

  • Celebrity Photos: April 2014

    Jamie Lynn Sigler was spotted purchasing a Rembrandt whitening kit at Target in New York on April 7.

  • Celebrity Photos: April 2014

    Faith Hill and Tim McGraw at the 2014 Academy Of Country Music Awards at the MGM Grand Hotel & Casino in Las Vegas, Nevada on April 6.

  • Celebrity Photos: April 2014

    Miranda Lambert and Blake Shelton at the 2014 Academy Of Country Music Awards at the MGM Grand Hotel & Casino in Las Vegas, Nevada on April 6.

  • Celebrity Photos: April 2014

    Carrie Underwood at the 2014 Academy Of Country Music Awards at the MGM Grand Hotel & Casino in Las Vegas, Nevada on April 6.

  • Celebrity Photos: April 2014

    Taylor Swift at the 2014 Academy Of Country Music Awards at the MGM Grand Hotel & Casino in Las Vegas, Nevada on April 6.

  • Celebrity Photos: April 2014

    Cameron Diaz made an appearance on "Wetten, dass..???" TV show on April 5 in Offenburg, Germany.

  • Celebrity Photos: April 2014

    Heidi Klum attended the "America's Got Talent" red carpet event at Madison Square Garden on April 4 in New York City.