Sarah DeLeon's mom says she is "not going away" after a judge dismissed a murder charge against the suspect in her daughter's cold-case killing

After more than 27 years, Gail Elieson thought she was finally getting closer to justice for her 18-year-old daughter Sarah Jo DeLeon, who was found stabbed to death in 1989 in Kansas City, Kansas.

But Elieson’s hopes were dashed last week when a judge in Wyandotte County, Kansas, dismissed the murder charge against 48-year-old Carolyn Heckert, during a preliminary hearing.

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“He was the jury,” Elieson said about the judge’s decision. “Instead of letting it go before a jury to decide, he decided, ‘Nope, she’s not guilty.’ ”

Heckert had been the prime suspect in DeLeon’s death. Her arrest last year was an apparent break in the nearly 30-year-old case.

“[The judge] didn’t feel there was enough evidence to take to a jury trial,” Jonathan Carter, spokesman for the Wyandotte County District Attorney’s office, tells PEOPLE.

Carter says that if new evidence arises, prosecutors can refile the charge, as there are no statute of limitations on murder.

Image zoom Carolyn Heckert Kansas City, Kansas Police Department

The investigation into DeLeon’s homicide had grown cold, but it was reopened in 2014 when authorities believed forensic technology could generate new leads in the case.

It seemed they were right: At a June news conference last year, Kansas City police described the person of interest as a female and a “romantic rival.”

Investigators said they also believed there was a case in nearby Independence, Missouri, that was linked to DeLeon’s death. In January 1994, Diana Ault was found shot to death inside her home while her two children, ages 4 and 8 months, were unharmed.

No one has ever been named as a suspect or charged in Ault’s case.

For decades, Heckert’s name has been mentioned in connection with DeLeon’s death. Despite the suspicion surrounding her, she married and was raising two daughters in Smithville, Missouri, where she was a real estate agent.

She was charged in October with first-degree murder in DeLeon’s stabbing. Her bail was set at $1 million but later reduced to $500,000.

After the judge determined there was insufficient evidence to move forward, Heckert returned home to her family.

“The whole time, she has been upset about her circumstances,” her attorney, John P. O’Connor, tells PEOPLE.

While Heckert is free, DeLeon’s mother is left wondering whether she’ll ever learn what truly happened to her daughter.