Gardai need to find Deirdre Jacob's body to convict someone of her murder, according to a retired cold case detective.
Today is the 24th anniversary of her disappearance in Co Kildare.
Aged 18, Deirdre Jacob went missing as she was walking home in Newbridge on July 28th, 1998.
Gardai believe she was murdered, but no one's ever been convicted.
Rapist and attempted murderer, Larry Murphy, has long been a suspect in the case.
But the DPP recently decided the gardai didn't have enough evidence to charge him.
Alan Bailey was formerly the lead detective in the Garda Cold Case Unit, says he remains a major person of interest in the case
He says Deirdre's body needs to be found to solve the case.
"If the body is located tomorrow morning I've no doubt it could be carefully examined.
"With all the advances in DNA testing, there is a possibility of locating some piece of evidence."