Murder-accused believed he had to kill 'to save Armidale' from aliens: court told

The now 49-year-old has pleaded not guilty to killing his 43-year-old friend at a property on the outskirts of Armidale in mid-June, 2017.

Neither man can be identified for legal reasons.

Dressed in a black suit and navy shirt, and supported by family in the courtroom, the accused sat in the dock of the NSW Supreme Court in Armidale on Monday as the evidence was presented in front of the deceased's family.

Justice Stephen Campbell will determine whether the accused is guilty of murder, or not guilty by special verdict of mental illness; and whether he was suffering from "a mental illness of the mind" at the time of the death.

The court was told the accused was diagnosed as a paranoid schizophrenic at age 16 or 17, and his behaviour had changed in 2017 after the death of his father and a change in medication.

The victim was stabbed in the neck. 

His body wasn't discovered until the next morning, after it had been dragged to the backyard, his hat placed "neatly" on him and his boots beside him.

The accused later made the comment that "he had to do that to save Armidale", the Crown told the court.

It's the Crown's case the then 47-year-old "stabbed his friend" while he was lying down or sitting down watching television.

The court heard evidence on Monday that, at the time, he would not have been able to "escape", as he was supposed to be wearing a moonboot and using crutches after having fallen from a horse.

"He was simply not in a state to be able to escape from the accused," the Crown prosecutor said.

The Crown claims the accused "killed [the victim] in the delusional belief" that it was the only way to save Armidale from "some attack, whether it be alien or otherwise".

The judge-alone trial began on Monday morning and is hearing evidence on seven key areas.

They include: the accused's behaviour in the lead-up to the killing and observations by his colleagues at work; the interactions between the accused and the deceased; the former's behaviour at the time of the killing and after; the autopsy and forensic evidence; and psychiatric evidence.

The evidence of two psychiatric experts is not disputed and both have arrived at the same conclusion on the accused's state of mind at the time.

It will be up to Justice Campbell to determine a verdict at law, or a special verdict by way of mental illness.

The trial continues.

Northern Daily Leader