Bitter River by Julia Keller

A teenage girl is found dead in car submerged in Bitter River outside a small West Virginia town.  Quickly it becomes obvious that it was no accident.
Bell Elkins is prosecuting attorney for the county of which Aker's Gap is a part.  As she works with the county sheriff, Nick Fogelsong, she discovers that Lucinda Trimble, a sixteen year old young woman with a very promising future, was also pregnant.  Nick and Bell soon learn that in spite of her kooky hippie mother's objections, Lucinda had planned to marry her boyfriend and raise the child.
The boyfriend and his wealthy family come under scrutiny as do Lucinda's friends, her heartbroken mother, and other residents of Aker's Gap.
Keller writes Bell as more than just a prosecuting attorney searching for a killer.  She is the mother of a daughter the same age as the murdered girl and friend to a man that Nick wants out of Acker's Gap. The two main characters and residents of the town must also deal with an apparent sniper shooting as well as an explosion in a local haunt.
The plot may seem familiar, but there are some interesting twists and turns and, most importantly, the characters are ones whose lives you'll become involved in and come to care about as they solve this whodunit.