90's mystery series of a female hired assassin

[thaxsar]

A friends mother is trying to find a book series she read in the 90's. She doesn't recall the author or character names. This is what she remembers:

Rich woman, father dies. Finds out he has lost the family's money. All he taught her was to shoot. She becomes a hired assassin. Because of her social standing she gets into all the right parties and no one suspects her because she's a woman. She only kills people she thinks deserves it, like pedophiles.

Thank you very much if can help!

FOUND Girl controls shadows

[aeiden]

I know I have this books somewhere, but I'm not sure where so here is what I remember of it...

The main character is a girl and her father has always favored her sister over her because she is prettier. It is revealed throughout the story all the times that he has physically and mentally abused her. So, one day she decides to run away from home on horse and when she gets to the main market area he finds her there and tries to bring her back. She screams and these shadow creatures appear, scaring the horse and killing the dad. She runs away and then gets caught by the authorities for killing him. She is about to be put to death when a famous group of magic users show up and save her then bring her back to their secret hideout to try and teach her how to use her power. I can explain a bit more but that's those are the main parts of it.

EDIT: I have found this book with a little more research. Sorry to bother you all. The book is 'The Young Elites' by Marie Lu