Stephen Wayne "Shorty" Jamieson, is serving a life sentence for leading a gang of five youths in the 1988 abduction, rape and murder of Janine Balding.
Jamieson has long claimed he was the victim of mistaken identity having been mixed up with another man who went by the same nickname, Mark "Shorty" Wells.
In an ongoing appeal before the NSW Supreme Court, the now-58-year-old has argued DNA testing of a bandana used to gag Ms Balding could implicate Mr Wells.
Mr Wells' DNA profile was obtained by NSW Police from Queensland authorities, however the parties were at odds over the legality of it being used for testing in the investigation.
On Monday, Justice Ian Harrison ruled Police Commissioner Karen Webb could legally use her powers to comply with Jamieson's request for the testing to take place.
"The interests of justice and the public interest in maintaining the integrity of convictions call for the testing to be undertaken," the judge wrote in his decision.
"A failure to conclude the investigation by conducting the tests and making the comparisons would in my opinion create an enduring sense of community unease."
Justice Harrison ordered the parties to make further submissions on how the testing could be carried out following his ruling on the legality of the testing.
Mr Wells has denied any involvement in the rape or murder and has never been charged over the crime.
During a previous hearing, the court was told Jamieson had been excluded from having provided the DNA on the bandana to the surprise of many in the courtroom at the time.
The partial profile of 11 genetic markers lifted from a part of the bandana did not match the full 21-marker profile of Jamieson, nor the three other males convicted alongside him, the court was told.
Assuming it was a single male, the partial DNA profile would match about one in five million individuals.
Jamieson's lawyer Richard Wilson SC previously argued that it would be "powerful evidence" to support his client's contention he was innocent if Wells' DNA profile could not be excluded.
Ms Balding's murder shocked the nation in its brutality after the bank teller was grabbed from a Sydney train station by the gang of homeless youths, who repeatedly raped her.
The 20-year-old was bound, gagged and thrown over a fence before being held underwater in a dam until she drowned.
Jamieson's appeal will return to court in March.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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