For Deb Tilson, the holidays will never be the same.

On Dec. 19, 2007, her daughter Kristine Larson was supposed to show up at her home in Minnesota to bake holiday cookies. Nearly seven hours later, the 19-year-old was found strangled in a burning car.

Larson’s ex-boyfriend, Zachery Matthews, who was also the father of her 2-year-old son, was convicted of her murder in 2008 and sentenced to life in prison without parole.

Tilson’s real-life nightmare is chronicled on Oxygen’s docuseries “Homicide for the Holidays,” which explores how brutal crimes across the country that occured between Thanksgiving and New Year’s. Tilson told Fox News she chose to come forward and relive the tragic tale for the series in hopes of raising awareness on domestic violence.

“My daughter was the youngest of four and very much the youngest by eight years,” said Tilson. “She was everyone’s baby in the family. She was that little spark who lit up our lives. She was very gregarious. A caregiver.

“She knew she had to make a better life for herself and her son. She had things put all in order. She had just gotten a job. In two weeks she would have graduated from bartending school and she was also enrolled in a nursing college.”

(Oxygen)

Larson began dating Matthews in 2004. In 2006, the couple welcomed a child named Darion. But in May 2007, Larson ended her relationship with Matthews. At the time of the murder, Larson and Matthews were no longer living together.

Tilson said that before the killing, Matthews, who endured a turbulent upbringing, was initially welcomed by the family.

“At the time, my husband was still mentoring him,” she explained. “We invited him to our home. We weren’t on bad terms with him… We just wanted to keep things on a low-key level with him.”

However, Tilson was horrified by what may have been occurring behind closed doors. While Larson didn’t share much about Matthews to her after their breakup, Tilson had learned through her daughter’s friends that she once reportedly remarked she had never been hit so hard by anyone in her entire life.

Tilson admitted that when her daughter went missing, she initially didn’t suspect Matthews.

“I just felt like for as much as he tried to get her back and wanted to be involved in her life — I was just in denial,” she explained. “I just thought anyone who knew her couldn’t do something like that to her. And I just felt that if it were him that meant their son wouldn’t have either parent. I was in denial. I felt like he really did love her and he wouldn’t do something like that to her. And that something like this couldn’t happen to this poor little boy.”

Kristine Larson with her son Darion. (Oxygen)

Pioneer Press reported that during the trial, a prosecutor contended that Matthews became enraged because Larson was a half-hour late in coming to his apartment to pick him up and take him to pick out Christmas gifts for their son.

The local newspaper shared that Matthews struck Larson with a blow that police said knocked her unconscious. He then tied the ends of a white shoelace into loops, treaded one loop through the other, placing it around her neck. Matthews pulled so tightly that the shoelace embedded in her skin.

Investigators believed Larson’s murder occurred in front of their son.

Pioneer Press added Matthews then carried Larson’s corpse out to her car, put her in the back seat and drove to a random alley. He then parked the car, tore some pages out of a phone book and set them on fire.

Before Matthews was suspected of murder, he was grieving with Larson’s family.

“I was just horrified,” said Tilson. “I felt so much darkness and sorrow… So many lives were lost over a poor decision made by someone who was obviously mentally ill.”

Zachery Matthews at Darion's birth. — Oxygen

Tilson claimed Matthew has been diagnosed with several mental health diseases, including multiple personality disorder and schizophrenia, among others. She added his troubled childhood may have played a role in his heinous actions.

“I truly believe he figured, 'If I couldn’t have her, no one else could,'" she explained. “We were his family. We were all he knew. He was in foster care for up until 16 when he emancipated himself. I think he figured, if she was out of the picture, there would be no drama. He could still be a part of our family in his own twisted judgment.”

“And I think Kristine thought that with as much love as she could give him, she could build him back up and change the negative self-esteem and control issues he had,” she added.

In 2009, the South Washington County Bulletin reported Tilson and her family got custody of Darion. She said raising her grandson, who is now 12, has been bittersweet.

“He keeps Kristine’s memory alive,” she explained. “He has a lot of her mannerisms, her smile and her laugh. However, he is a product of his father as well. So those things rear its ugly head.

“He’s been diagnosed with tons of emotional disorders. Reactive attachment disorder, possibly bipolar, ADD. He’s prone to having blackout rages. He has a lot of issues with control because when he was a baby, he witnessed all of this. And he was powerless. … We’ve had a long road with him. He’s come a long way. And I gotta tell ya, we wouldn’t trade it for the world.”

Zachery and Darion. (Oxygen)

Tilson said the maximum security prison where Matthews is currently located is only a 20-minute drive from her home. However, she said it’s been a year since she had heard from Matthews, who reportedly insisted he was innocent up until two years ago.

And while Christmas is a joyous time for countless families, it’s a haunting reminder for Tilson.

“Our family traditions… have changed because of this,” she said. “Some of my kids are still very angry… We were the ideal family, like The Waltons. We all got together. Everybody laughed. We shared meals. I have my moments where I’m really strong and empowered. And then I have my moments where I’m just a mess… We don’t bake cookies anymore. The holidays just aren’ the same.”

Still, Tilson said she is determined to see Christmas in a different light. Her goal is to commemorate the season with those who have no one to share the holidays with.

But Tilson refuses to let her daughter be forgotten with time. She explained that right after Larson’s death, she was contacted by the Minnesota Coalition of Battered Women, which has helped her cope with her grief. She hopes her story, and Oxygen’s show, will help other young women get out of terrifying relationships before it’s too late.

“It’s the elephant in the room no one wants to talk about,” she said. “That’s why I got involved. Especially this time of year.”

(Oxygen)

"Homicide for the Holidays" airs Dec. 9th at 8 p.m. on Oxygen.