A man with paranoid schizophrenia cut his step-grandmother’s throat because he thought she was a witch, a court heard.
Jonathan Griffiths, 23, pleaded guilty to manslaughter after killing Janice Griffiths at their home at Ty Rhiw in Taff’s Well, near Cardiff, on June 12, 2017.
The 59-year-old, who was also known as Rose, had raised him since he was a baby and was his legal guardian.
Judge Eleri Rees, who sentenced the defendant at Cardiff Crown Court, said: ‘It is shocking and tragic that she should die at the hands of someone she did so much for during her life.’
Michael Jones QC, prosecuting, described how carpet fitter Dennis Martin Jones had pulled Griffiths off his grandmother after she had shouted for help.
The defendant was standing over her with a large hunting knife with a ‘18.7cm’ blade, while she was on a sofa.
Mrs Griffiths told Mr Martin to call 999 after her grand-son had slit her throat.
The defendant continued his attack by twisting her neck as if he were trying to break it, the court heard.
Mrs Griffiths was rushed to University Hospital of Wales, in Cardiff, via air ambulance but died the next day after suffering a ‘devastating brain injury’ that was caused by a sharp force injury to the neck.
Griffiths was arrested at Cardiff Road and told officers he had wanted to ‘rip her head off.’
He later told police he had killed his grandmother because she was a ‘white witch’.
Griffiths had been experiencing hallucinations prior to the killing and was also heard quoting the bible.
The Crown accepted a guilty plea to manslaughter after experts said there was diminished responsibility. The charge of murder to lie on file.
Griffiths is currently in Ashworth Hospital, in Liverpool.