Antonio Fanni was also injured during the lunchtime attack on Monday at the apartment he shared with his mother-in-law Anna Melis and his 67-year-old wife Maria Melis in the village of Baunei near the city of Nuoro.
His wife is not critical and is expected to stay in hospital in the nearby town of Lanusei for two weeks, while Fanni will be discharged from the hospital in 10 days' time.
Police recovered a knife with a 16-centimetre-long blade from a patch of weeds outside his apartment building which they believe he used to attack Melis and her mother during an argument.
A judge was due to decide if Fanni can be held criminally responsible given his dementia diagnosis.
An autopsy was expected to be performed on the murder victim.
Fanni and Melis have five children.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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Doraiah Chowdary Vundavally is a Software engineer at VTech . He is the news editor of SocialNews.XYZ and Freelance writer-contributes Telugu and English Columns on Films, Politics, and Gossips. He is the primary contributor for South Cinema Section of SocialNews.XYZ. His mission is to help to develop SocialNews.XYZ into a News website that has no bias or judgement towards any.