A man who poses a 'seriously high risk to the public' has been sentenced to life in prison with a minimum of 12 years for the 'sustained and forcefully violent' killing of his father.

Joe Walker stabbed his 65-year-old father, Tom, multiple times in the head and neck during a frenzied attack at their home in Fir Street, Nelson in May 2020, while in the grip of a serious psychotic episode.

A post-mortem examination found that Tom likely suffered 'stamping' to his head and body, before Walker made attempts to clean the house with bleach and arranged the scene, turning his father's body face-up and placing a knife in his hands.

At Preston Crown Court on Thursday Judge Simon Medland said: "Some of the injuries sustained were consistent with Tom Walker defending himself and he would have, in those moments, known that his own son was killing him."

The court heard how Walker, who was a habitual cannabis and cocaine user, first taking the class B drug aged 11, and later aged 25 beginning to use the class A stimulant, had been sectioned in April last year, just weeks before he killed his own father, due to erratic behaviour caused by a withdrawal from prescribed anti-depressants and an adverse reaction to lockdown restrictions, which had left him paranoid.

He had launched an attack on his dad prior to his detainment on April 4, with both Tom and his ex-wife Janet, Walker's mother, attending the local police station to report concerns over their son's mental health.

Prosecuting, David Toal said: "They told police the defendant had become obsessed with the coronavirus and what he was reading on social media after being furloughed from his cleaning job.

"This had led to Joe punching his father and then threatening him with a knife, with Tom describing his son as 'unpredictable'."

Walker was sectioned and tested positive for cocaine and cannabis, but was discharged from Royal Blackburn Hospital just days later on April 11, returning to live with his dad.

Then, tragically, on May 22, in the early afternoon, Janet Walker received a hysterical phone call from her son telling her his father was dead.

Mr Toal went on: "The police were called and found the defendant in an agitated and distressed state, rocking back and forth at the bottom of the stairs with self-inflicted cuts to his body.

"He told the police 'my dad is dead'.

"Officers entered the living room and found Tom lying on his back surrounded by a pool of blood.

"Both arms were across his body and a knife had been placed in his hand."

Blood was found in several rooms of the house, including upstairs, none of which matched that of Tom, but did match that of the defendant.

Walker had attempted to clean himself and the knife using bleach, and investigators found no evidence that Tom had been assaulted or bled in any other area of the property.

Mr Toal added: "His death was the consequence of a sustained and forceful multi-mode assault."

Victim personal statements from Tom's siblings spoke of the family's 'unbearable' devastation at the loss of a 'quiet man with a huge caring heart, who loved his son unconditionally'.

Judge Medland said: "This is a tragedy. The family is devastated knowing this was no stranger but his own son who ended his life.

"You were psychotic but had taken cannabis and cocaine for many years and it is known that these drugs can have detrimental effects on a person's mental wellbeing.

"You took those drugs voluntarily and they exacerbated your mental state. Although you suffered from psychological problems for some years you had never experienced a psychotic episode but, you took cocaine and cannabis, and had been diagnosed as being dependant on those drugs and doctors concluded that your mental instability was exacerbated by your drug use.

"You subjected yourself to mental upset by continuing to take these substances, and it was to a significant degree your own fault that you suffered psychosis, and I say your attack on your father was linked to your drug taking.

"You may have an underlying susceptibility to mental health disorders but your drug taking exacerbated it and you descended into homicidal psychosis.

"And it is my view you pose a seriously high risk to the public."

Walker pleaded not guilty to murder but guilty to manslaughter by reason of diminished responsibility and will serve a minimum of 12 years in a mental hospital, less 556 days for time already served.

If he is ever deemed eligible to leave the hospital he will serve the rest of his sentence in prison, and if granted parole, will be subject to an automatic recall to prison for life.