The family members convicted of murdering a Rakaia farmer in 2019 have appealed their convictions on the grounds of an unfair trial.

Dairy farmer Tony Grant Waldron was bludgeoned to death while he slept in his Gardiners Road home in Rakaia in September 2019.

His injuries were so bad that police initially thought Waldron had been shot.

The body of the father of two young girls was discovered by a co-worker after Waldron failed to turn up for milking at 5.30am on September 18.

The pair appealed their murder convictions in the Court of Appeal in Christchurch yesterday with their lawyers claiming an unfair trial.

Post-mortem evidence indicated Waldron, 29, had been struck at least three times with a solid weapon, leaving injuries to the side of his head, ear and neck including a broken jaw and fractured skull.

Police launched a homicide investigation codenamed Operation Gardiner, searching a vehicle, a couple of properties in Rakaia and Christchurch, and the Rakaia and Selwyn riverbeds. The National Dive Squad also helped with a search of irrigation and effluent ponds but the murder weapon was never found.

Waldron’s estranged 35-year-old wife Alana Jane Bamber and her cousin Joshua Dylan Morris-Bamber, a 28-year-old chef, were charged with murder and convicted.

The pair denied murdering Waldron or having any part in his death.

The Crown case was that Bamber encouraged her cousin to assault Waldron, who she claimed had been having an affair. Bamber provided her cousin with Waldron’s address on the night of the murder.

The Crown alleged Morris-Bamber drove from Christchurch to Waldron's farm, with cellphone data and CCTV from NZTA cameras picking up his movements.

His car was captured passing a golf course going in the direction of Gardiners Road at 12.56am.

The same car is seen passing the same golf course again, heading back to Rakaia, at 1.04am.

With driving time, the Crown claimed Morris-Bamber had "at least four minutes" at Waldron's home, which they claimed was "ample time" to go inside and fatally assault him while he was sleeping.

However, Morris-Bamber claimed he went to talk to Waldron but had second thoughts when he arrived and did not enter the property.

A jury found both Bamber and Morris-Bamber guilty of murder in October 2022.

In December 2022, Justice Gerald Nation sentenced Morris-Bamber to life imprisonment with a minimum non-parole period of 16 years. Bamber was given a life sentence with a minimum non-parole period of 13 years.

Yesterday their lawyers argued that the conviction of Bamber and Morris-Bamber relied heavily on evidence from a witness who told police she saw a message from Morris-Bamber asking Bamber for Waldron’s address and saying he wanted to let out some anger.

Morris-Bamber denied sending the message in his evidence.

The appeal lawyers argued that the witness changed her story, mentioning the message in her third statement – and only after the police offered her immunity from prosecution for perverting the course of justice. They argued that she had a motive to lie while the Crown argued that the witness had initially forgotten about the message.

Bamber's lawyer Kerry Cook said Justice Nation should have provided a warning to the jury on how to evaluate potentially unreliable witness testimony. The Crown argued that it was clear from the court proceedings and cross-examination that they needed to evaluate her evidence, and calling special attention to her testimony would be unfair to the witness.

Cook said Justice Nation stopped cross-examination of the witness over some messages that would have highlighted some credibility issues, while the Crown argued that the messages were not relevant to the case.

Cook further said that Justice Nation did not tell the jury that Bamber was not required to give evidence and that should not be counted against her. The Crown argued that this was not a requirement.

James Rapley KC, appearing for Morris-Bamber, said the alleged message was relied on "heavily" in convicting Morris-Bamber.

He said there was no forensic evidence that he was in Waldron’s house, none in his car, his home, or where he was alleged to have disposed of items.

But there was evidence that he went to Waldron’s address and the disputed message was used for the “why and intentions”, Rapley said.

He disputed that Morris-Bamber was angry and the "anger message" only surfaced after the witness was offered immunity.

The appeal lawyers also objected to the immunity documents being put before the jury.

The wording in that document said the witness had been offered immunity for telling the truth. The lawyers argued that this could sway the jury to believing it meant the witness had told the truth.

“The immunity certificate was misleading,” Rapley said.

The Crown argued the document was submitted as evidence for transparency.

Bamber's lawyers also appealed her sentence and put forward an argument that she should have been given more credit for her first conviction at the age of 35 and her personal circumstances.

The three Court of Appeal Justices, Susan Thomas, Christian Whata, and Francis Cooke, will consider the case and release their decision in the coming weeks.

By Sharon Davis