William Kean was found guilty by a jury of battering the 80-year-old widow to death in her own home in February.
Kean, 47, a former police special constable, had blamed the murder of Mrs Methven's son David.
But there was substantial forensic evidence which linked Kean to the scene of the killing at the pensioner's Forteviot home.
William Kean was found guilty by a jury of battering the 80-year-old widow to death in her own home in February.
Kean, 47, a former police special constable, had blamed the murder of Mrs Methven's son David.
But there was substantial forensic evidence which linked Kean to the scene of the killing at the pensioner's Forteviot home.
After today's verdict at the High Court in Glasgow, David Methven issued the following statement: "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 as 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.
"I thank the jury for their verdict and the sentence will leave him with plenty of 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."
David Harvie, procurator fiscal for the north of Scotland said: "This was a sustained and brutal attack which left an 80-year-old widow dead in her own home. Her murder has shocked the local community.
"William Kean was a long-time friend of Jenny Methven and her family and was a frequent visitor to her home. That she met her death at the hands of someone she knew and trusted makes this murder all the more harrowing."
