A murder investigation has been launched after the death of an elderly woman described as a \"wonderful mother\" and \"true friend\". Pensioner Janet Methven was found injured in her home by her son. She died in the Kildinny Farm cottage they shared in Forteviot, Perthshire, at about 5.15pm on Monday, as an ambulance was called. The 80-year-old\'s death is now being treated as murder. A post-mortem examination carried out in Dundee showed Mrs Methven, known as Jenny, sustained injuries to her head and body, Tayside Police said. Her son, David Methven, said his mother\'s death has \"absolutely devastated\" him. He said: \"As well as being a wonderful mother, she was an extremely generous person, someone who was a true friend to others and always willing to give her energies and time freely. \"I miss her desperately and would appeal to anyone who can assist Tayside Police with their inquiries to get in touch with them. I would also like to take this opportunity to thank local residents and others who have expressed their sympathies and sorrow at what has happened. Their kind words do offer some comfort and I am grateful for that. \"I also appreciate the media\'s interest and would ask them to continue to support the police investigation to establish what has happened. However, I would also ask that they provide me with space and time to grieve in private.\" Detective Chief Inspector Colin Gall appealed for the help of householders and businesses in the Strathearn valley. He said he hopes private properties and business premises in the area have CCTV footage which might help the inquiry. Officers are forensically examining Mrs Methven\'s property. Police say they have found no sign of forced entry to the cottage or of any property being stolen but are keeping \"an open mind\". Mr Gall said CCTV footage could be \"invaluable\" in figuring out what happened to Mrs Methven