Mystery Killer : A nun

Suzanne was illegitimate daughter of the well-known at that time in Paris, Mr. Jean.
Mother had betrayed him when he was swimming.
The girl was born very beautiful and absolutely was not like her sisters Sophie and Mary.
From early childhood, and his father and mother did not like her, but Mr. Ying Janet did not know about the betrayal of his wife.
Suzanne grew up in monasteries and a novice, and when it came of age, the mother forced her to become a monk at the monastery
St. Anne.
Exactly one month after the adoption of dignity dies, Mr. Janet, and Susan comes home to say goodbye, and after the funeral, the mother was dying, she was poisoned !!!
Who is involved in these murders?
Really sister decided to divide the inheritance parents?
Suzanne will all understand ... Who is to blame ???