THE son of murdered pensioner Jenny Methven described his former friend who carried out the brutal killing as "beneath contempt" as he was sentenced to life in prison.

David Methven, 58, said he would never forgive William Kean (pictured) who was found guilty of murdering the charity volunteer in her home in a ferocious attack. A judge ordered Kean to spend the next 22 years in jail before he is eligible for parole.

Mr Methven found his 80-year-old mother's body lying in a pool of blood in the cottage they shared in the quiet village of Forteviot, Perthshire, when he returned from work on February 20.

During Kean's trial at the High Court in Glasgow, a recording of his frantic 999 call to the ambulance service was played to the jury, in which he was heard desperately trying to revive his mother.

Mr Methven said: "No verdict will bring my mother back or spare her the terrible ordeal that took her life.

"I will never be able to imagine her suffering in those moments or comprehend the cruelty of a man who would do that to an elderly woman who regarded them a friend to the family.

"Billy Kean was a friend of mine for more than 20 years. In fact we were almost like brothers. I cannot begin to understand or forgive what he did to my mum. It was an act of betrayal and his denials in the time since and particularly during this trial leave him beneath contempt."

He added: ''I thank the jury for their verdict and hope that the sentence he has been given leaves him with plenty time to reflect on the devastation he has caused – not just to my family, but to his own family too.

"I am also very grateful to local residents and others who knew my mum and know me well. They have been a great support throughout this ordeal. My mother was warm, generous and someone who always had time for others around her. I miss her desperately.''

What drove the first offender, a former special constable with Tayside Police, to kill Mrs Methven remained a mystery last night.

Sentencing, Judge Lord Glennie ordered Kean to serve at least 22 years of his life term before being eligible to apply for parole.

He highlighted the brutality of the killing, in which Kean beat Mrs Methven to death, striking her more than 11 times with enough force to shatter her skull and force pieces of bone into her brain.

He continued the attack despite the fact she would have been unconscious and dying after the second blow.

Kean, of Blairgowrie, Perthshire, had continued to rain down blows on his defenceless victim.

Lord Glennie told him: "You have been convicted of the murder of Jenny Methven.

"The brutality of the murder of which you have been convicted – of a kindly, active older lady who was a relative of one of your friends – means a lengthy sentence must be imposed."

The murder led to one of the biggest operations mounted by Tayside Police, with 80 officers spending weeks conducting door-to-door inquiries, studying CCTV tapes and tracking down people who had been in the area on the day of the murder.

More than 400 potential pieces of evidence were recovered during forensic inquiries at Mrs Methven's cottage.

Kean was eventually caught after CCTV footage was found showing his car heading towards Forteviot at around the time of the murder.

An investigation of the crime scene also uncovered his bloody fingerprint in the house, his DNA on Mrs Methven's body and a pair of trousers with her blood on them hidden in his garage.

He denied the murder and lodged a special defence incriminating David Methven, saying Mrs Methven had been killed by Glasgow gangsters operating at her son's behest.

In evidence, he claimed to have found Ms Methven badly injured in her home but did nothing to help.

He claimed her son, Mr Methven, had threatened to kill him if he went to the police.

But Detective Chief Inspector Colin Gall, who led Tayside Police's investigation into the murder, dismissed Kean's claims as complete fantasies.

He said: ''William Kean has offered a version of events in court that bears no resemblance to the reality of what happened.

"He has only compounded the suffering for Mrs Methven's son. Not only did he murder David's mother, he betrayed his friendship and then sought to incriminate him for his mother's death.

''I am pleased that the jury rejected his claims and have ensured that justice is served. I hope that Jenny's family and friends can draw some solace from the fact that Kean will now pay for his actions."