THE family of a woman murdered in her home have called for repeat offenders to be locked up until they die after the man who stabbed her to death was jailed for at least 26 years.

Isabelle Sanders, 51, was killed and her partner Norman Busby, 86, was seriously injured by Paul McManus, who burst into the couple's house in Crookston, Glasgow, in the middle of the night armed with two knives.

McManus, 20, had been released from the latest of many periods of detention just weeks before he attacked the pair, stabbing Mr Busby twice in the chest before repeatedly knifing Ms Sanders 37 times and inflicting a further 24 injuries on her.

At the High Court in Livingston, Judge Lord Armstrong told McManus he had been convicted of "a vicious attack characterised by sheer brutality" and would have to serve 26 years before he could be considered for parole.

If he eventually secures his freedom he will be on licence and subject to recall for the rest of his life.

However, speaking outside court, Ms Sanders's brother James Dougall and sister Lindsay said they planned to lobby MSPs to change judges' sentencing powers so that "life means life".

Mr Dougall said: "We would like to acknowledge Lord Armstrong who, given current judicial protocol, has imposed as severe a sentence as likely in this case.

"However, we strongly believe that for violent reoffenders who flagrantly disregard the rehabilitation offered and opportunity given to them through early release who then go on to commit a violent murder, that the Scots judiciary should be given the option and the guidance to impose a whole of life sentence.

"We will be petitioning the Scottish Parliament to urge the Government to consider this opinion."

McManus had denied murdering Ms Sanders, who was known as Izzy, but admitted stabbing Mr Busby on April 9 last year. He was convicted by a jury after a trial which heard that he had entered the house to try and steal the car which was sitting outside.

Defence QC Gordon Jackson said there was little that could be said in the accused's favour apart from the fact that he had a "tragic" life story. He had rarely attended school, never worked and led a "chaotic lifestyle" which had resulted in offending.

He added: "Undoubtedly on the night of this happening there was a substantial ingestion of drink and drugs.

"Nothing will mitigate or excuse what happened here. The only thing that I can say is that he was at that time only 19. One can only hope that he'll change. If he does it will give him some hope and some timescale when he might come back to join us in the wider community."

Sentencing McManus, Lord Armstrong highlighted his "significant" criminal record, which included convictions for theft, assault and robbery and the use of weapons.

Despite his young age, he pointed out that McManus had already served seven sentences of detention and had murdered Ms Sanders a matter of weeks after his release from custody.

He told McManus: "There are no reasons, whether to do with the consumption of drugs and alcohol or your lifestyle otherwise, which could possible justify the taking of another's life as you did.

"I have no doubt that those who knew Isabelle Sanders and her relatives have been deeply affected by all this. No sentence would be regarded as sufficient in their eyes."

He imposed a life sentence with a punishment part of 21 years for the murder and a consecutive sentence of five years for the attempted murder and other offences.