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!