Sainey Marong says his murder trial conviction was an injustice as he had untreated diabetes and was insane at the time of sex worker Renee Duckmanton’s murder.
He told the Court of Appeal – Justice Mark Woolford, Justice David Collins, and Justice Forrest Miller – that the jury was not told that when the police pulled him over in his car he was behaving oddly, but his behaviour was not unusual for a mentally impaired person.
The court has been sitting in Christchurch to hear local cases for two days.
Marong said the Crown had no legal authority to prosecute him according to the Criminal Procedures (Mentally Impaired Persons) Act.
This meant Marong was unable to communicate properly with his lawyer, and the Act said that if he had a communication deficit, knowledge, understanding or comprehension problems for conducting a defence, that amounted to a significant partial impairment, he said.
Marong tested positive and was diagnosed after his arrest, with diabetes, but his medical records were misrepresented at the trial, and his worsening kidney function, and other problems in prison were not disclosed to the jury, he said.
Justice Miller said the Crown had two expert witnesses at Marong’s trial who were both very clear that Marong was not insane. They said that untreated diabetes was capable of causing a disease of the mind but that wasn’t the case for Marong.
Mark Lillico, representing the Crown, said at the trial Justice Cameron Mander had no hesitation in allowing the defence theory that it was an insulin deficiency that led to the murder, but all the expert evidence said it didn’t reach that threshold.
An amicus curiae (a helper to the court), Fiona Guy-Kidd, said there had been as assessment early in the trial where Marong was found fit to stand trial.
She said there was a diagnosis of an adjustment disorder with a depressed mood after he was imprisoned, but it was not relevant to his mental state at the time of the homicide. The evidence at the trial was that Marong was trying to silence Miss Duckmanton.
Marong said the diagnosis after the offending was not relevant, and the jury should have said he was not guilty by reason of insanity.
Justice Miller said they were reserving their decision, which will be delivered within a few weeks.
Marong, an Ilam butcher, was found guilty by a jury of murdering the 22-year-old sex worker in May 2016, in what Justice Mander called a “particularly callous and cruel” way.
He strangled her after they had had sex, and then burned her body which was found on a roadside near Rakaia the next day.
Crown prosecutor at the trial, Pip Currie, said Marong’s internet searches on his computer were about murder, kidnapping, and necrophilia.