Dead as a Doornail (Sookie Stackhouse #5) by Charlaine Harris

Sookie Stackhouse enjoys her life, mostly. She's a great cocktail waitress in a fun bar; she has a love life, albeit a bit complicated, and most people have come to terms with her telepathy. The problem is, Sookie wants a quiet life - but things just seem to happen to her and her friends. Now her brother Jason is about to turn into a werepanther for the first time. She can deal with that, but her normal sisterly concern turns to cold fear when a sniper sets his deadly sights on the local shifter population.

She's afraid not just because Jason is at risk, but because his new were-brethren suspect Jason himself may be the shooter. Sookie has until the next full moon to find out who's behind the attacks - unless the killer decides to find her first.