Definitely Dead (Sookie Stackhouse #6) by Charlaine Harris

Sookie Stackhouse doesn't have that many relations, so she really hated to lose one - but of all the people to go, she didn't expect it to be her cousin Hadley, a consort of New Orleans' vampire queen - after all, Hadley was technically already dead.

But Hadley is gone, beyond recall, and she's left Sookie an inheritance, one that comes with a bit of a risk - not least because someone doesn't want Sookie digging too deep into Hadley's possessions. . . or her past. Sookie's life is once again on the line, and this time the suspects range from rogue weres to her first love, the vampire Bill. Sookie's got a lot to do if she's going to keep herself alive . . .