Published: May 10, 2013 1:22 PM EDT
Updated: May 10, 2013 4:17 PM EDT

CAPE CORAL, Fla.- Today marks 23 years since a horrific double murder in Cape Coral, and still the case remains a mystery.

Robin Cornell and her babysitter were raped and murdered. Robin's mother won't stop fighting for justice.

She was a smiling, happy, 11-year-old girl, whose life was brutally cut short.

"I promised the day I had to say goodbye that for as long as I was alive, I would never stop looking," said Jan Cornell.

She will never forget May 10th, 1990. That was the day she found her daughter and 32-year-old Lisa Story, dead in their Cape Coral house on SE 12th Avenue. Both were sexually assaulted and suffocated.

Decades later, this double-murder is still unsolved.

"I can take her flowers to the cemetery, and I can keep looking for the man who hurt her so she can have justice. Because they deserve justice," Jan said.

The case has been featured on America's Most Wanted, and despite evidence collected, like a set of keys and DNA, police have no suspect to match the DNA profile.

But the Cape Coral Police Department says this is not a cold case, just an "old case." And 23 years later, they're still following tips, and re-examining evidence.

Police say it's never too late to submit a tip. Any little piece of information could help crack this case. You are urged to call Crime Stoppers at 1-800-780-TIPS, or the Cape Coral Police Department at (239) 574-3223.