Daniel de Costa had taken an 'industrial quantity' of the anti depressant valium in the hours before he stabbed Matthew Baggott to death, a jury at Winchester Crown Court heard today.

Defence witness, consultant psychiatrist Dr Paul Cantrell, in his reply to a question from His Honour Judge Guy Boney QC, confirmed that de Costa had told him he had got a prescription for 350 milligrammes of valium, also called diazepam, the day of the stabbing and taken the lot.

“That’s a huge dose isn’t it? Five times the average dose I think?” asked the Judge.

“An industrial quantity,” confirmed Dr Cantrell.

The court also heard that de Costa had been drinking sherry that day as well.

Dr Cantrell had told the court that he had interviewed de Costa in prison after the killing of Mr Baggott and had reviewed over a thousand pages of medical evidence from doctors who had examined de Costa over the years.

He was convinced that de Costa was suffering from adult ADHD (Attention Deficit Hyperactivity Disorder) and that this constituted an abnormailty of mind under the Homocide Act.

This would mean that de Costa cannot be found guilty of murder, though guilty of manslaughter.

But Dr Frank Farnham, a consultant psychiatrist appearing for the prosecution, said he had also reviewed the medical evidence and was not convinced de Costa had ever suffered from ADHD.

He said: “He (de Costa) certainly suffers from a severe personality disorder and some of his symptoms can be found in ADHD. He uses violence in an instrumental fashion with a plan to get what he wants. There are going to be times when he acts impulsively and others when he uses violence in quite a planned way.”

He added that many of de Costa’s symptoms were indicative of a psychopathic condition which could also be seen as an abnormality of mind.

The trial continues.