What is the title of the old movie about a man who kills to be earl or duke?

Its an old movie and in black and white. Its about a man whose mother was in line to become duke or earl but because she married out of her class she and her family were put on the end of the list. Her son decides to become friends with these family members and slowly kills them off to become the next duke or earl. He has a best friend in this movie that is a girl. Her name is Sabellla. Any help for the title of this movie would me much obliged.|||This is a great movie called Kind Hearts and Coronets.|||Jurassic Park