AUSTIN, Texas — Even though Austin’s notorious yogurt shop murders occurred nearly 28 years ago, Cold Case Unit detectives at the Austin Police Department say that solving the crimes remains their top priority.

Investigators have renewed their focus on the events that occurred on December 6, 1991. That evening, four teenage girls were shot to death at the I Can't Believe It's Yogurt shop in North Austin. The store was then set on fire.

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Two men later admitted to the murders in signed confessions, which they later recanted. They went on trial and were found guilty of murder by juries in Travis County.

But the convictions were overturned by the Texas Court of Criminal Appeals, which ruled that the confessions had been used improperly at their trials. 

They were to be re-tried when something unexpected happened.

WATCH: KVUE Crime Files: Exploring the 1991 Austin yogurt shop murders

“To get ready for those re-trials, the DA’s office resubmitted evidence to try to get DNA profiles,“ said Travis County District Attorney Margaret Moore. “It was in that process that a piece of DNA was developed that did not match any of the suspects.”

Moore said the decision was to dismiss the cases pending further investigation, “namely trying to identify that little piece of DNA.”

“The APD Cold Case Unit picked the case back up and decided we need to take a fresh look at all of this,” Moore said. “Once they picked it up, they came and met with me and asked us to meet with the families of the girls.”

Moore said she told the families of the girls that “we will never give up on this case.”

Investigators meet regularly with the Travis County DA’s office, and they are seeking assistance that may help them to identify the mystery DNA.

WATCH: KVUE Crime Files: The families of the 1991 Austin yogurt shop murder victims still have hope

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“We’re conferring with and meeting with the scientific community that are schooled in DNA,” said Cold Case Unit Homicide Detective Brad Herries. “We want to understand the current technology available, the current tests that are available and how we can identify this DNA sample.”

At the Cold Case Unit offices in North Austin, investigators often return to a locked room filled with rows of file cabinets that hold thousands of pages of interview transcripts, news clippings, tips and court documents that pertain to the murders.

“We still get tips, and we still conduct interviews,” said Cold Case Unit Homicide Detective Ryan Metcalf. “We are hopeful that somebody, somewhere knows something and that they can provide the information we need to bring this case to a resolution.”

WATCH: KVUE REWIND: One year after the Austin yogurt shop murders (October 23, 1992)

EDITOR'S NOTE: This piece is Part 3 of the "KVUE Crime Files" series examining the 1991 Austin yogurt shop murders. You can view Part 1 here and Part 2 here.

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