I have already read this, it was a TOR freebee way back when... but it was such a good book I am going to nominate it here...
Four and Twenty Black Birds by Cherie Priest
Although she was orphaned at birth, Eden Moore is never alone. Three dead women watch from the shadows, bound to protect her from harm. But in the woods a gunman waits, convinced that Eden is destined to follow her wicked great-grandfather--an African magician with the power to curse the living and raise the dead.
Now Eden must decipher the secret of the ghostly trio before a new enemy more dangerous than the fanatical assassin destroys what is left of her family. She will sift through lies in a Georgian ante-bellum mansion and climb through the haunted ruins of a 19th century hospital, desperately seeking the truth that will save her beloved aunt from the curse that threatens her life.