Hour Game by David Baldacci

Second Hand 

ADVENTURE / THRILLER. Following their collaboration in Split Second, ex-Secret Service agents Sean King and Michelle Maxwell have gone into partnership and are investigating the robbery of some secret documents at the residence of the incredibly wealthy Battle family. It seems like a straightforward case of domestic burglary, but soon they begin to suspect links to larger, more terrifying events now shaking the prosperous town of Writghtsburg ...The unidentified corpse of an attractive young woman turns up in the woods; two high school kids, one shot in the back, the other in the face, are found dead in their car; and, a successful lawyer is discovered stabbed to death in her own home. A serial killer is on the loose.