TULSA, Oklahoma - 15 years ago, Brittany Phillips was buried after being found raped and murdered in her South Tulsa apartment complex.

The case has never been solved and it took a big step backward recently when detectives learned, the DNA found at the scene, did not belong to the killer.

Brittany's mother, Maggie Zingman, says there's been a lot of confusion since police announced the DNA found at the scene belongs to someone who is not a suspect, which means, with no DNA in this case, tips are more important than ever to solve this case.

"They found DNA on the sheets, semen that matched a small sample of blood. The DNA from two sources from the same person, they thought logically, they thought that was the killer," said Maggie.

The DNA from the scene was used to create a composite sketch of what the suspect might look like. Detectives say they received hundreds of tips and one of those tips led them to a man.

Investigators compared his DNA to the DNA from the scene and it was a match. For a brief moment, they thought they finally had their killer, until they spoke with that man and others and learned of his whereabouts at the time and determined, he was not the killer after all.

"The hole in my heart that I learned to live within my heart, it just opened up and bled and I was just overwhelmed," said Maggie.

She and police had pinned their hopes on that DNA from the scene but, since that is no longer the case, they know nothing about the killer.

"He could be African American, Hispanic, Polynesian, German. He could be anyone," said Maggie.

Maggie says she has great faith in the cold case detective but would love other cold case experts from around the country to also take a look at the case, just for a new perspective.

Maggie is held a Tulsa Cold Case day of caring at LaFortune Park over the weekend with families, police officers, and lawmakers in attendance. She also wants to create a Cold Case support group for all the families in the area, waiting on an arrest in a murder case.

Brittany Phillips: