Spectre - Phaedra Weldon

Next in the series that's 'art paranormal whodunit, part urban fantasy' (Publishers Weekly) by the author of Wraith.

Zo Martinique has the extraordinary ability to travel outside her body at will. When she is drawn into an investigation of a series of bizarre murders, in which the victims are missing body parts, Zo hopes to help her boyfriend, Atlanta homicide detective Daniel Frasier, stop the killer-one she's sure is from the darkest levels of the astral plane-without letting him find out about her special abilities.

Then danger strikes close to home when Zo's mother disappears, and Zo must use all the powers at her command to save her-even though Zo knows that, in doing so, she may make herself into something no longer entirely human.