Poison Ivy (1992)
Not a "true" story mind you. But it also involves two young girls forming a strange infatuation with each other, and culminates in the murder of a parent
It's Chinatown
Dolores Claiborne has a bit of the same feel I think.
shareFun (1994).
The greatest trick the Devil has ever pulled was convincing the world he didn't exist!
Also, in one of his interviews, director Eli Roth has actually mentioned that this movie was among the cinematic inspirations for his black comedy psychological thriller "Knock Knock" (2015) with Keanu Reeves, and surprisingly enough, one of the things at least it DOES have in common is two young ladies (even though its teenage girls in this movie) going over the line and committing violent crime.
The greatest trick the Devil has ever pulled was convincing the world he didn't exist!
Fried Green Tomatoes
"Strange. It seems like a character mutation".