A Toronto man was sentenced to 3 1/2 years in prison for manslaughter in the death of his elderly mother by failing to properly care for her.

Donald Noseworthy, 55, physically and mentally abused his 78-year-old mother Mary, who suffered from Alzheimer's and was bedridden, unable to care for herself. The senior was also kept near starvation.

Noseworthy's mother died from congenital heart failure, but Justice Edward Then found him guilty, ruling the woman died from the stress of being abused by her son.

The judge convicted Noseworthy of manslaughter and failing to provide the necessities of life in February.

Noseworthy is believed to be the first person in Canada to be convicted of manslaughter, in other words an unintentional killing, in a case of elder abuse.

Crown prosecutors believe the ruling sends a strong message about caring for elderly parents.

"It sends out the message that if they're to care for the elderly, their parents, they're not to abuse that position," prosecutor Rosemary Juganovich said outside court on Tuesday.

Noseworthy's sentence is on top of 21 months he has already spent behind bars awaiting trial.

His lawyer argued that period in custody should be considered long enough.

With a report from CTV's John Lancaster