A Quebec woman has been formally charged with second-degree murder in connection to the death of an elderly woman on Montreal's South Shore.

Ellen Dennett, 58, appeared at the Longueuil courthouse Tuesday to face the charge. She was arrested  Monday.

Kathleen Livingston, 78, was found dead in her Brossard home  early Saturday morning after a friend notified authorities.

Her friend told police she had not heard from Livingston for several days and was worried about the wheelchair-bound senior.

Authorities say Livingston and Dennett knew each other and had been living in the same house for several weeks.

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Longueil police are investigating the incident. ((Radio-Canada))

Investigators are trying to establish the nature of the relationship between the two women, through interviews with Livingston's neighbours on Béliveau Street.

A neighbour of the senior, who spoke on condition of anonymity, told CBC News a caregiver moved into the house about two months ago. 

Dennett will return to court on August 30, according to crown prosecutor Sacha Blais.

Neighbourhood in shock

Residents in the Brossard neighbourhood where the senior lived said they are relieved at news of the arrest.

However, many said they still don't understand how this could happen on their quiet suburban street.

"Taking a woman in a wheelchair, and 78 years old, it's unbelievable," said Jean Barsalou.

Flowers were placed on the woman's doorstep in the days following her death.