A TEENAGER who murdered his grandmother by stabbing her 23 times as she slept was today locked up for life.

Thomas McAlpine was just 15 when he killed 60-year-old Elizabeth McAlpine after a row about his performance at school.

Judge Lord Clarke said McAlpine, now 16, would serve at least 12 years before he could be considered for parole.

The judge told McAlpine at the High Court in Edinburgh: "The evidence in this case clearly established you subjected her to an attack of such savagery it almost beggars belief.

"Only you perhaps will ever know why someone who had apparently done you no harm and had, indeed, cared for you, should have been subjected to such savagery.

"The impact on your family and particularly on your sister who had to witness the aftermath of such an attack can only be imagined. If you have any human feelings, that in itself will be punishment for you."

The teenager had claimed he loved his granny and blamed sleeping pills for the killing.

But a jury rejected his claim that he was not responsible for his actions and found him guilty of the brutal murder.

Defence QC Donald Findlay today asked Lord Clarke to consider the sleeping pills as a possible explanation.

The lawyer said although McAlpine denied murder, he had not denied the killing.

Mr Findlay added: "I have never known a case where anyone has killed their grandmother. Even in the worst of families grandmothers have a sacred position."

Asking for a minimum sentence equal to the jail term for the lesser offence of culpable homicide, Mr Findlay said: "It would give a young man who has not had much of a life so far some kind of hope for the future."

The trial had heard how McAlpine, of Waverley Terrace, Dumbarton, killed his gran in the house on June 15 last year, just hours after Mrs McAlpine told him she was going to wash her hands of him if he didn't buck up his ideas at school.

After she went to bed McAlpine got a knife from the kitchen and stabbed her 23 times.

The noise and the shouts of her grandmother woke his sister Elizabeth, 17, who went into the room and found the dying woman covered in blood and crawling along the floor.