SPOKANE, Wash. -- Spokane Police believe they have solved the brutal murder of 12-year-old Marsi Belecz. Marsi was found stabbed to death back in August of 1985. 

Police say it was DNA technology that led them to Marsi's killer. He is no longer alive.

Spokane Police identified the killer as Clayton Giese, a Montana native. Giese was 22-years-old at the time of the rape and murder. He died in a car crash in 1989. His body was exhumed this year, and DNA recovered matched what was found on Marsi’s remains.

During the investigation, detectives looked closely at 87 suspects, 12 were cleared by DNA.

KHQ's Hayley Guenthner featured Marsi's case last March in her Q6 Cold Case series. She again spoke with Marsi's sisters who are trying to come with terms with the news they had waited to hear for decades.

Marsi's sister Star says while she's grateful for answers, she wishes she would have been able to ask Marsi's killer one thing.

"Why, I would have asked him why," she said. "What happened?"

Another sister of Marsi's, Donna Vanzant, told KHQ she has felt frozen on that awful day. The day she learned her little sister was viciously murdered.  

She says a detective called her earlier this month and broke the news she had been desperate to hear for years.

"I'm still in disbelief," Donna said. "But I'm happy at the same time. I feel free like a big weight has been lifted off of me."

Donna admits she had given up hope. 

"I didn't think it would ever be solved while I was alive," she said. 

She says her family is incredibly grateful to SPD.

"I want to say thank you to all of them," she said. "They did a good job even when I had doubts, they were doing their job."

And that was to work a case that was as disturbing as it gets.

"She was raped and stabbed more than 29 times," Donna told KHQ in a 2019 interview.

Donna was 17-years-old at the time. She remembers her final moments with her sister.

"It was the first time she had bought a new outfit," Donna told KHQ in 2019. "She bought a mini dress sand jelly shoes. She was proud of herself for that. We never got to do that because we had a strict family."

Donna said Marsi bought the outfit with her allowance money. She said their father made it clear he didn't like the outfit. Marsi was very upset and left the family home.

"She was hurt more than anything, she got hurt easily," she said. "She gave my mom a hug, said 'I love you.' That's the last time I've seen her."

Donna says their mother reported Marsi missing. Police were looking for her. But it would be an employee of a towing company who would find Marsi's body. She was dumped behind an old building on the property just east of downtown Spokane. 

Donna said they have since learned Marsi met her killer at a party she went to that evening.

"She was also beaten, she had bruises on her face," she said. "Her entire face was all swollen."

Donna knows that because she said she had to make a positive ID.

"They came to the house with pictures," she said. "Her eyes were closed. I know how she looked with her eyes closed. I that's Marsi."

Detectives told reporters back in 1985, the murder was likely not committed out of lust but rather rage. The shock of it all took over Donna's life.

"It's really hard," she said in our 2019 interview. "At first when it happened, when I'd see a group of people, I'd think I'd see her. Sometimes I'd even chase them down and say, 'Marsi come back.'"

Donna said she finds some comfort in the fact that the man who did this was not someone they knew or trusted. She says she is grateful for Spokane Police for never giving up.

Marsi’s sisters asked our “Help Me Hayley” for assistance in finally securing a headstone for Marsi. They say they never could come up with enough money to cover the cost for one.

“Her killer has one, but my sister doesn’t. It’s not right.”

If you have any resources that could help this family, email Hayley at hayley@khq.com.

THIS IS A DEVELOPING STORY. MORE INFORMATION WILL BE AVAILABLE SOON.