Questions raised about DNA evidence used to convict a man of murdering a German tourist have been characterised by the Crown as simply a "spat between experts".
In 2007 Michael Scott Wallace was jailed for at least 18 years after a jury found him guilty of murdering Birgit Brauer near New Plymouth two years earlier.
Wallace is appealing against his conviction for murder.
Wallace's lawyer said an expert he consulted had found material on the metal bar, said to be the murder weapon, from a person unrelated to Ms Brauer and it was in the interests of justice for that to go to a jury.
However, the Crown lawyers said that was a debating point between experts and not something the Court of Appeal should use to rule the evidence was unsafe.
The Crown accepted the DNA evidence produced at the trial was controversial, but said it supported other circumstantial evidence relating to Wallace.
Defence lawyer Greg King also told the court his client had always denied that a fingerprint found on Ms Brauer's diary was his. However, contrary to Wallace's instructions, his trial lawyer never challenged that evidence.