Pandey-Johnson's lawyer Michele Wilkinson-Smith told the court this morning that the key police witness - who spent almost a week in the stand during the five-week trial - was unreliable.
The key witness, who has name suppression and is known simply as CW29, was in the bedroom when Mr Browne was bashed to death, but was granted police immunity against prosecution if she gave evidence against the accused.
Mr Browne was killed in a Wellington flat on January 21, 2010.
On the instructions of Pandey-Johnson, the leader of a drug-dealing gang, Nuku repeatedly struck Mr Browne over the head with a hammer before his body was dumped in the garage of a New Plymouth house.
Ms Wilkinson-Smith said CW29 should have been one of the accused, not a witness.
In her evidence, CW29 said she woke to Mr Browne being bashed and admitted administering about 20 milligrams of liquid morphine to Mr Browne to ease his pain after being bashed.
Ms Wilkinson-Smith said CW29's evidence should not have been admitted and in fact she should have been up on murder, manslaughter and class A drug dealing charges.
"If the case is built on an unreliable witness...the case is flawed."
All evidence "pointed to her being in it boots and all".
Ms Wilkinson-Smith said CW29 was never fully honest with police, and said text messages about a kidnap plot pointed to CW29 being involved much more in the case than she let on.
Ms Wilkinson-Smith called into question the cause of Mr Browne's death and said it had not been excluded by a crown expert witness that the morphine injected by CW29 did not kill Mr Browne.
The witness said it was unlikely, but it was not ruled out completely.
The level of morphine injected into Mr Browne would have been fatal to any healthy person, she said.
"The question must be, what did kill him?...the morphine was capable of killing him.''
Ms Wilkinson-Smith gave the example that if Mr Browne had been bashed and then someone came along and shot him, he would have died of a gunshot wound and those that bashed him could be convicted only of attempted murder.
The cause of death was not clear-cut and Ms Wilkinson-Smith said the trial judge should have highlighted this to the jury in the summing up.
Cause was not properly considered by the jury, she said.
"It is possible that he died because he was injected with morphine,'' she said.
"Alarm bells should have been ringing.''
However, one of three judges hearing the appeal, Justice Terence Arnold, said Ms Wilkinson-Smith should have supplied an affidavit from an expert which said Mr Browne could have died from a morphine overdose, which she had not done.
Nuku's lawyer, Lester Cordwell, said the text messages, behaviour before and afterwards, and to a certain degree things she said in statements, brought CW29`s evidence into disrepute.
She could easily have been prosecuted, he said.
CW29`s refusal on six occasions to answer questions about the morphine injection also created problems during the trial, he said.
"There is no clear statement that it was done after the blows...there's no clear statement about how long after the blows when the morphine was injected,'' he said.
She was given ample opportunity to give evidence about the timing of the morphine injection, but she repeatedly refused to answer questions.
"As it stands, there is no evidence of when the morphine was injected.''
It left a massive gap in the narrative which meant the jury was not able to answer what the substantive cause of death was.
Nuku's defence was that CW29 killed Mr Browne, meaning she "had every reason to give dishonest testimony''.
The crown had not excluded that Mr Browne could have died after falling into a coma after being injected with morphine, he said.
Crown lawyer David Boldt said the direction from the judge was "absolutely spot on''.
The evidence said that the beating Mr Browne suffered was fatal, and maybe added to that was an injection of morphine, Mr Boldt said.
Evidence given at trial that Mr Browne died as the result of blows to the head was consistent with toxicology reports.
The evidence also went unchallenged at trial, Mr Boldt said.
"The Crown did prove causation at trial.''
"We have a substantial, and thus far unchallenged, body of evidence.''
The inability to challenge the cause of death at trial was not a moment of insanity by the trial defence lawyers, rather an ``entirely rational response to the evidence given''.
