Kyle Ellis, of New Hall Road, Ruabon, Wrexham, a paranoid schizophrenic, admitted the manslaughter of widow Susan Hannaby, 69, on the grounds of diminished responsibility.
A hospital order without limit of time was made with a bed available at Ty Llywelyn medium secure unit at Llanfairfechan. He is now subject to a restriction order affecting any release.
Judge Rhys Rowlands at Mold Crown Court said Ellis had been “spoiled rotten” by his grandparents from the age of 14 and psychosis was the only explanation for the killing in an “explosive loss of control” in February last year.
He remarked: "There’s absolutely no motive for this at all. He was close to his grandmother.”
The judge told Ellis: "It’s plain you wouldn’t have committed this dreadful crime were it not for your very severe mental illness at the time. That illness hadn’t previously been diagnosed.”
Judge Rowlands said Mrs Hannaby lost her life in a “sustained and brutal” attack in her home shortly after midnight on February 11 during which a neighbour heard screams.
The grandmother had been strangled seemingly with a dressing gown cord and stabbed in her face and chest. Ellis then tried to set fire to her body by placing it on the hob before disabling a smoke alarm and leaving the house.
Prosecuting counsel Anna Pope said Ellis had claimed to be a victim of childhood abuse. He’d stopped his cannabis use, but family and friends were worried about him.
During the killing of the pensioner she suffered a broken jaw. He’d left knives in her body.
The barrister said he had shown “delusional” behaviour and Ellis suggested his gran was the “demon.”
Gordon Cole KC, defending, urged the court to make a Mental Health Act order.