A man accused of murdering Sean Miles after beating and stripping him and dumping him in a river did not understand the gravity of the situation because he is autistic, a jury heard yesterday.

Terry McMaster, 24, of Alice Smith Square in Littlemore denies murdering Mr Miles on May 1 last year.

A trial at Oxford Crown Court heard from an expert witness that McMaster has a mild form of Autism, called Asperger's Syndrome, and would not have grasped the seriousness of the attacks on Mr Miles.

Julian Baughan, defending McMaster, told the jury if they decided McMaster killed Mr Miles, of Herschel Crescent in Littlemore, they must agree it was committed with diminished responsibility.

John Mallen, a neuropsychologist, carried out tests on McMaster while he was in custody and said the results showed he suffered from undiagnosed autism.

The trial had earlier been told McMaster hit Mr Miles on the head with a knife then, with three others, beat him and drowned him in the River Thames over claims he interfered with a boy of four. Mr Mallen said: "He would not have a full understanding of what happened.

"The suggestion is people with Asperger's Syndrome are unable to put themselves into other people's shoes and understand how that person is feeling. He might understand what they were doing was wrong, but only on a conceptual level."

Edward Doyle, 34, Tracey Fathers, 35 and Karen Fathers, 35, also from Alice Smith Square, deny murder.

The trial continues.