A lawyer for a teenager accused of murdering a 34-year-old civil servant said yesterday that one of his friends was responsible for the fatal attack.

Robbie McIntosh, 16, who is on trial at the High Court in Forfar, denies repeatedly stabbing Anne Nicoll, whose blood-stained body was found on the Law Hill in Dundee.

Peter Gray QC, Mr McIntosh's defence counsel, suggested the accused's friend Robert Soutar, 16, had ''butchered'' Miss Nicoll, after she threatened to tell his mother he had been smoking cannabis. He also alleged Mr Soutar had claimed to have committed the killing the following evening. Mr McIntosh's lawyers have lodged a special defence of incrimination, blaming Mr Soutar for the murder.

However, Mr Soutar, who gave his occupation as a ''meat technician'' and whose address was give as care of Tayside Police, insisted he was with another friend at his grandmother's house in the city at the time the murder was alleged to have taken place.

Miss Nicoll had set off from her home in Byron Street, Dundee, to walk a dog in the area of the hill at about 6.30pm on August 2 last year. Her body was found hours later by her boyfriend Gordon McKenzie, 33.

During examination by Brian McConnachie, advocate depute Mr Soutar said he had spent the early evening of August 2 - between 6pm and 9pm - watching DVDs at his grandmother's with his friend Dean Montgomery, 16. Mr Soutar admitted in court that he had carried a knife which his mother had subsequently discarded when she discovered it in his bedroom.

The court heard that Dean Montgomery, who was also a friend of Mr McIntosh, had made the knife with a blade and part of a brush handle, before later giving it to Mr Soutar.

The court also heard that Mr Soutar suffered from attention deficit hyperactivity disorder, and that he had stopped taking medication for it last April. Mr Gray suggested that Mr Soutar's ability to control himself was ''more difficult'' when not taking medication and with alcohol.

However, Mr Soutar denied this, adding: ''I can control myself when I'm drinking.''

Asked by Mr McConnachie why he had the knife, Mr Soutar replied: ''Protection,'' saying he occasionally got into trouble.

Mr Gray suggested that the accused and Mr Soutar had been smoking cannabis when they were spotted by Miss Nicoll, who threatened to tell the witness's mother. He suggested the victim walked past Mr Soutar before he took the knife from his back pocket and ''butchered'' her.

However, in re-examination by the advocate depute Mr Soutar denied the defence counsel's suggestion that he would have been ''unhappy'' if Miss Nicoll had threatened to tell his mother about the cannabis.

The trial continues.