Heather Graham 
Keeper of the Dawn [EPUB ebook] 

A deadly killer on the loose…Alessande Salisbrooke has heard that human sacrifices are being carried out in LA by the followers of a shape-shifting magician. As a Keeper, Alessande understands the risks of investigating, but she can’t shake the feeling that the killings are tied to a friend’s recent murder…With the help of Mark Valiente, a dangerously sexy vampire cop, Alessande narrowly escapes becoming a sacrifice herself. But as the bodies pile up, drained of blood, one truth becomes clear: no one — not even those you care about the most — is who they seem.