Michael Cardamone, 50, has now pleaded guilty to the violent murder of Karen Chetcuti Verbunt in January 2016, admitting he drugged the Whorouly woman with an animal tranquilliser, bound and gagged her, before fracturing her skull and using petrol to set her alight.

He is due to face a plea hearing on August 21.

But earlier this year, he worked with his mother Maria Cardamone to arrange for a prosecution witness to be killed ahead of a possible trial before a jury.

The 78-year-old appeared in Wangaratta Magistrates’ Court on Thursday, via videolink from Dame Phyllis Frost Centre.

Dressed in a bright blue jumper, Maria Cardamone – an Italian native – appeared to struggle to understand most of what was said in the courtroom, but gave a clear answer when magistrate David Faram asked how she pleaded.

“Yeah, I’m guilty,” she said.

Barrister Rob Stary said his client could understand enough English to give her instructions.

“Mrs Cardamone will enter a plea of guilty to one count of attempting to pervert the course of justice and there will be no application for bail,” he said.

The charge of incitement to commit murder was withdrawn.

Maria Cardamone was arrested in May this year and refused bail because homicide detectives feared she was a danger to other witnesses in the case.

Detective Senior Constable Steven Eppingstall told the court at the time she had become “fixated” on the man she believed had been more responsible for the death of Ms Chetcuti Verbunt than her son.

Police intercepted phone calls between Maria Cardamone and her son from jail in March, where they used code to discuss killing the witness.

The mistake was giving the job to an undercover police officer posing as a hitman, who agreed to be paid in two installments of $12,500 before and after the job.

The case was adjourned for a plea hearing at the Wangaratta County Court circuit, starting on August 28.