A leading law professor suspects Malcolm Rewa won't be sentenced to life in prison without parole despite the horrific nature of his crime.
Rewa will be sentenced on Tuesday for the 1992 murder of Susan Burdett, after a jury returned a guilty verdict in February in his third trial for the murder.
The two previous juries had failed to decide if he was guilty of the crime.
Mark Henaghan, a professor of law at the University of Auckland, said Rewa would be given a serious sentence, but he didn't believe it would be life in prison without parole - a sentence never given before in New Zealand.
"He will definitely get life because it is murder... I suspect he may get some term of parole at the end," he told The AM Show.
A key reason Prof Henaghan gave for why Rewa may be given a parole period is that he only committed one murder. He said other criminals who committed multiple murders hadn't been given life without parole, and the judge would need to be consistent.
"When you compare it with other cases, it was multiple murders, this is one murder but it was a brutal murder," he said.
"He has got to be consistent with other cases, and at the end of the day if people have committed multiple murders and haven't got life without parole, then someone who has committed one murder... it may be difficult to say are you being consistent."
The professor also said the judge would need to focus on the crime before him, not Rewa's previous sentences for rape.
"The difficulty is that you have just got to look at this particular crime, and it was an awful crime in the sense that he breaks into someone's house, rapes them and brutally murders them with a baseball bat, so the gravity of the offending is quite high."
Burdett's body was found in her Papatoetoe home in March 1992.
Teina Pora was wrongly jailed in 1994 for her murder when he was 17, but two decades later, his conviction was quashed and he was awarded $3.5 million in compensation.