Man who stabbed his friend 37 times believed he was acting in self defence, court hears

• ITV Wales' Richard Morgan reports.

A man who killed his best friend by stabbing him 37 times believed he was acting in self defence, a court has heard.

Dylan Thomas is accused of the murder of William Bush on Christmas Eve last year.

Thomas has previously admitted manslaughter on the grounds of diminished responsibility.

On the fifth day of the trial, Dr Panchu Xavier, a consultant forensic psychiatrist at Ashworth High Secure Hospital, where the defendant is being treated for schizophrenia, told the court he believed Thomas had been psychotic "for many months" before the fatal incident, and had formed the opinion his life was under threat.

"My view is that he was convinced he was going to come to harm", Dr Xavier said.

"If that is what you think, you are going to try to eliminate that threat."

"In his mind, that's why he behaved as he did. He felt threatened by his best friend and that's why he responded as he did."

The trial has previously heard that Mr Thomas initially stabbed Mr Bush in his bedroom, before chasing him down the stairs of the 3 storey house they shared in Cardiff where the assault continued.

Mr Bush sustained serious wounds to his neck and died at the scene.

Describing the defendant's beliefs - based on conversations he's had with him since - Dr Xavier said Mr Thomas "holds onto the view" that he felt threatened by Mr Bush.

"He holds onto the view that he did this in self defence", Dr Xavier said.

"It is the only explanation he has in his mind. It is the only explanation that allows him to carry on living."

Cardiff Crown Court has previously heard that Dylan Thomas had told William Bush that he'd "thought about killing him" several months before the fatal incident.

The night before Christmas Eve, he carried out searches on the anatomy of the neck while staying at his grandmother's house in the Vale of Glamorgan.

Dylan Thomas also messaged Mr Bush, asking him if was still at the house they shared together, adding that "he needed to see him" before Mr Bush went home for Christmas.

The jury was told that, the following morning, the defendant's grandmother drove him back to the house in Llandaff, where Thomas armed himself with two knives before attacking the 23 year old.

Asked about the suggestion that the defendant's ability to plan meant he had formed a "rational" intention to kill William Bush, Dr Xavier said it did not.

"Even psychotic people can make plans and say what they will do today, tomorrow and the next day."

"My view is that he was psychotic before, psychotic at the time of the incident and that he had schizophrenia."

The court also heard about an incident in November last year when Dylan Thomas was arrested after trying to scale a 14 foot fence at Buckingham Palace.

Armed police were called and warnings were shouted to Mr Thomas. Eventually an officer rugby tackled him to the ground, the court heard.

Following his arrest the defendant asked the officers if he could have a tour of the palace.

He also claimed that the officers who'd arrested him could "hear his thoughts", something Dr Xavier was a "common psychotic belief."

Dr Xavier told the court that Thomas later told him he'd attempted to enter the palace because he wanted to "explore the energy field" of the building.

The psychiatrist was also asked about a letter Dylan Thomas had written to Elon Musk in which he claimed to have invented an anti-gravity device and technology to solve the world energy crisis.

This was despite the fact he'd failed his driving theory test a number of times.

Dr Xavier said this belief was "clearly psychotic."

"He was convinced he had the ability to do these things and the delusion he could do these things", he told the court.

"I don't think his academic ability would suggest he could develop this deep understanding of physics and gravity in just a few months."

"My view was that he was psychotic many, many months before the incident", Dr Xavier added.

Later, the court heard the evidence of another psychiatrist, Dr Dilum Jayawickrama, who interviewed the defendant after his arrest.

Dr Jayawickrama said he agreed with Dr Xavier that the defendant was suffering from an "abnormality of mental function caused by schizophrenic illness", but was unable to give a "psychotic explanation" for what he'd done to Mr Bush.

"I think there was an abnormality of mind but I do not think it substantially impaired [the defendant's] ability to understand what he was doing", Dr Jayawickrama said.

"I cannot give a psychotic explanation but there might be reasons beyond my expertise."

Dr Jayawickrama agreed that he didn't have all the information heard by the jury at the time he made his first report about Dylan Thomas

But after reading up to date reports about the defendant's condition, he agreed that Thomas "was suffering from a psychotic illness,, schizophrenia, in the months leading up to the incident."

Dylan Thomas, now 24 denies murder and the case continues.

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