Police investigating the fatal attack on Wellington journalist Phillip Cottrell say they are frustrated that a number of witnesses changed their evidence during the trial of two men accused of his murder.

Nicho Waipuka, 20, was yesterday found guilty of the manslaughter of Mr Cottrell by a jury at the High Court at Wellington.

His co-accused Manuel Robinson, 18, was cleared of all charges.

Mr Cottrell, who had brittle bones due to a genetic condition, was found fatally injured on Boulcott Street in central Wellington on December 10, last year.


He had been walking home from an overnight shift from his job at Radio New Zealand.

The trial lasted just over two weeks and the Crown called about 65 witnesses.

About half a dozen of those witnesses changed their evidence in court.

One of those witnesses, Waipuka's girlfriend Sylvanna Robinson-Stepien, told police after the co-accused were arrested that Waipuka had told her about the attack.

But under questioning by Crown prosecutor Grant Burston, Ms Robinson-Stepien, who is also Robinson's cousin, said what she told police was all a lie.

She said police were corrupt and her statements, which were put before the court, were not the truth.

Other witnesses associated with the co-accused also recanted their statements during the trial.

Detective Senior Sergeant Scott Miller, who was in charge of the case, said the change of evidence was frustrating and made it difficult to present the case to the jury.

But he said police were not looking into whether there was intimidation of the witnesses during the trial.

"It's really a case of the witnesses were family members or close associates of both of the accused - I think they made their own decisions.

"Whether there had been any assistance with that or not, I don't know.''