Christine and Léa Papin grew up in France in the early 1900s. They were abused by their mother and probably abused by their employer. They reached the tragic act of killing their employer and her daughter. The account of police on the scene:
Christine And Léa Papin - Killers (Hover)
International Level: International Guru / Political Participation: 1089 100%
If abuse is the reason then you might want to add that being mentally ill could also be part of it. Abuse could send you off so who knows. I think they both were just fed up with how messed up their life was and they took it out on the family.
International Level: Junior Politician / Political Participation: 87 8.7%
Being abused your whole life to the point that you do not know anything else it then becomes something much different. Now you are to the point that you feel that violence is a part of life. Violence begets violence and when something happens to make you snap you will do what you have yourself been subject to your whole life. SO yes I do feel that a life of abuse can make a killer.