The jury in the Daniel de Costa trial has been sent out to consider its verdict.

The six men and six women were sent out at 2.43pm today (Monday) and will have to decide whether the 31-year-old Melksham man was responsible for his actions when he stabbed 35-year-old Devizes man Matthew Baggott to death.

Summing up on day six of the trial at Winchester Crown Court His Honour Judge Guy Boney QC told the jury they must decide whether de Costa is guilty of murder or guilty of manslaughter on the grounds of diminished responsibility.

Central to that decision, he told them, is whether de Costa had suffered from Attention Deficit Hyperactivity Disorder (ADHD) from childhood.

One of the symptoms of the condition is impulsivity which may or may not have led de Costa to his actions on the day.

Judge Boney drew the jury’s attention to the transcript of a lecture by Australian ADHD expert Dr Caroline Stevenson which the jury was shown on the opening day of the trial.

Dr Stevenson believes that for de Costa to claim he had ADHD it would have to be proved he had it from before the age of seven. Although de Costa was not diagnosed until his late teens the judge said there was compelling evidence from his mother, Victoria Bull, that he was inattentive, hyperactive and impulsive from the age of two.

But he also noted opinions from two medical experts called by the prosecution, Dr Frank Farnham and Dr Mike Watts, who were not convinced that de Costa’s symptoms are consistent with ADHD.

Judge Boney also mentioned evidence from Ian Birleson, a detention officer at Melksham custody unit, where de Costa was brought after his arrest on September 6 2007.

Mr Birleson in his statement said that de Costa had made a comment about lowering the tariff for murder referring to the time he would have to spend in prison if found guilty.

Judge Boney said the jury would have to decide whether this comment was evidence of de Costa’s premeditation of Mr Baggott’s killing.

He also noted that lack of remorse at the consequences of his impulsive actions is also a symptom of ADHD.