Child sex teacher claims cops stuffed up, juror went rogue

A botched police investigation and a rogue juror who claimed they were bullied into delivering a guilty verdict are among the shocking allegations aired in an appeal hearing for a Sunshine Coast teacher convicted of child-sex offences.

Ex-deputy principal of Maroochydore State High School Kenneth Ralph Ernst, 61, was in September last year convicted of a number of child sex offences against a girl aged between 13 and 16.

The offences date back to the 1990s but the man was not charged until 2017.

Ernst was sentenced to three years' jail by the Maroochydore District Court after a jury found him guilty of 11 offences against the girl, who was not a student.

Ernst is appealing the conviction in the Queensland Court of Appeal on the basis there was a miscarriage of justice after it was revealed the investigating officer, Senior Constable Martin Willis, interviewed a college friend of the victim but did not disclose the information she provided.

The woman claimed the victim said she had been having a consensual affair with Ernst and that she had made up allegations of sexual assault in the past, the court was told.

During the appeal hearing on Tuesday, the court heard Sen Const Willis failed to disclose to either prosecution or defence that he had met the woman and did not take a statement from her, despite the allegations she made about the woman.

Court documents show the woman contacted Ernst's former solicitor after seeing a report on the television that the ex-teacher had been convicted, telling the man she was never contacted by police to provide a statement for the hearing.

Defence barrister Tony Glynn QC said her evidence would have been "devastating to the prosecution case had it been made available".

In giving evidence during Tuesday's Court of Appeal hearing, Sen Const Willis said he could not recall much of the details provided by the woman in an affidavit to the court.

Justice Peter Davis told the officer his notes of conversations with the woman were limited and was possibly the reason "why you're having trouble remembering those conversations".

Justice Walter Sofronoff later said "the police officer didn't even understand his obligations" for disclosing evidence and his notes were "almost non-existent".

During the hearing, Mr Glynn also argued the conviction should be set aside on the basis a juror approached Ernst's family and supporters after the verdict and told them he was bullied and threatened into finding the man guilty.

"He expressed some concern on how the verdict was reached and in particular how pressure was applied to him," Mr Glynn told the court.

The juror also allegedly said he thought the man should have been found not guilty but he was "bullied" and "yelled and sworn at in the jury room" when he expressed this view.

Crown prosecutor Dzenita Balic argued the witness who was not disclosed during the case would only have given evidence of the woman's credibility, not the substance of the case.

She said there was already evidence before the jury that the victim had a reputation for lying.

"Even if it goes to (her) credit, it's potentially devastating isn't it?" Justice Davis suggested.

The Queensland Court of Appeal have reserved their decision on the case.

Ernst will be eligible for parole after half of his sentence has been served.

Originally published as Child sex teacher claims cops stuffed up, juror went rogue