Jane Furlong was buried in different clothes to those she was last seen in, detectives revealed last night.
The teenager was reported missing in 1993 by her boyfriend Danny Norsworthy, shortly after she was last seen by friends on K Rd, Auckland.
Her remains were found at Sunset Beach, Port Waikato, two months ago.
Detective Inspector Mark Benefield, lead officer in the case, last night said investigators believed Ms Furlong could have been alive for several days after she was last spotted.
"The clothes Jane was found in [in] the grave ... are different to what she was wearing on Karangahape Rd in 1993," he told told TV3's 60 Minutes.
Mr Benefield did not reveal what clothes were found with Ms Furlong's remains, but said they differed to those friends last saw her in - a black dress and brown leather jacket.
"Those that are responsible for Jane's death know what she was wearing [when] ...
they placed her into that sandy grave," said Mr Benefield.
The change in outfit adds to the possibility the 17-year-old was alive for several days after she was last seen.
Mr Benefield also said it was likely Ms Furlong's murderer knew the Sunset Beach area well.
Police and Ms Furlong's family are appealing to those with information to come forward.
Mr Benefield said: "It's 19 years - it's a long time for a big secret ... to hold on to. Associations change [and] loyalties change."