17-yr-old Raonaid Murray’s body was found at Silchester Crescent in Glenageary, Co Dublin, just 300 feet from her home on 4 September 1999.
Gardai claim they have recently been in contact once again with the teenager’s friends and family.
They are asking those who knew Raonaid well to contact the investigation team at Dun Laoghaire Garda Station.
Raonaid worked at a clothes shop then known as Sally West in Dun Laoghaire Shopping Centre.
Raonaid left the shop at approximately 9pm on 3 September 1999 and went with a friend to Scott’s pub in Dun Laoghaire.
Tragically, she never made it to the nightclub and her body was found at Silchester Crescent at 12.33am, Saturday 4 September 1999.
Anyone with information is asked to contact the garda incident room at Dun Laoghaire Garda Station, phone 01-6665000/6665012 or alternatively the Garda Confidential line at 1800 666 111 or any garda station.
A reward for critical information received is available from Crimestoppers – 1800 25 00 25.