Mentally ill murderer's sentence increased

A man jailed for killing his father before murdering his 12-year-old neighbour and slicing the throat of her grandmother has had his sentence increased on appeal.

Renzo Da-Pra, 48, has had six years added to his sentence for the 2009 murder of Emma Wighton in her Wetherill Park home and causing grievous bodily harm to her grandmother Vivienne Wighton, 77, with intent to murder.

But on Friday Justice Robert Hulme and Justice Geoffrey Bellew also quashed Da-Pra's conviction for the manslaughter of Gino Da-Pra, finding him not guilty on grounds of mental illness.

But his sentence for the murder of Emma Wighton was increased from 10 to 13 years and he could stay in jail for a further seven.

He will also spend at least an extra three years behind bars for the attack on Mrs Wighton, after the judges increased his minimum non-parole period to seven years and six months.

The court on Friday heard shocking details of the killing of Emma Wighton, who died instantly after Da-Pra cut her throat twice with a hunting knife with such force it cut through to her spine.

Moments before, Da-Pra cut Vivienne Wighton's throat.

The court on Friday heard that after going berserk and attacking the women, Da-Pra went upstairs and substantially ransacked the house, leaving Emma dead and her grandmother unconscious and bleeding heavily from the throat.

Da-Pra's mental state was a key issue in the trial, with the jury told he believed he was under threat from a bikie gang, and that if he killed his father, he could save his mother from being tortured.

Three psychiatrists found he probably suffered some form of schizophrenia.

"The bikies were, on the appellant's later accounts, a critical component, perhaps even the single most significant component, of his delusions," the judgment said.

After Friday's appeal, Da-Pra will become eligible for release on parole on 19 December 2027.