Law student Victoria Cafasso was stabbed multiple times during a violent struggle in the middle of the day at Beaumaris on the state's east coast on October 11, 1995.
She had only been in Tasmania for five days and was visiting a cousin.
The initial police investigation into her death was criticised by a coroner, who found the beach where her body was found was not entirely cordoned off.
The scene was contaminated by foreign objects, including a tarpaulin, and wasn't recorded on video, while the forensic state pathologist didn't attend.
Tasmania Police on Friday released reconstructed images of a light-coloured Subaru station wagon, a car of interest in the early stages of the investigation.
Witnesses told police a man was driving the station wagon in the area at the time of the murder.
He was described as being in his 20s, about six-feet tall, with a slim, fit build and the appearance of a surfer.
A person matching that description was seen running on to the beach where Victoria was found.
Tasmania Police detective acting Inspector Andrew Hanson said investigators joined together the description of the driver and the running man after recently reinterviewing witnesses.
"That is probably the big link we have made," he said.
Insp Hanson said searches had been conducted on the east coast and elsewhere in the state in the past few months.
"The people of interest we identified back then … they still remain persons of interest because we simply haven't been able to rule them in or rule them out," he said.
A $500,000 reward remains available for information relating to a conviction in the case.
The coroner determined a blunt object and then a knife was used to attack Ms Cafasso and she suffered 21 stab wounds.
"Serious crime cases stay open until answers are found, and a person or people responsible are arrested and charged," Insp Hanson said.
"Victoria's family deserve closure and our detectives continue to work to try and provide that closure."
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