In Le Mans France in 1933 there are two sisters, a bloody & gruesome double murder, and possibly mental illness. Sources
https://papinsisters.tripod.com/crime.htm
https://www.theguardian.com/stage/2016/feb/24/the-maids-jean-genet-new-version-jamie-lloyd-uzo-aduba-zawe-ashton-laura-carmichael
https://www.thevintagenews.com/2018/08/10/papin-afair/?safari=1
https://murderpedia.org/female.P/p/papin-sisters.htm