Shadow Prey by John Sandford

Book 2 in this fabulous series. PW: In Shadow Prey, the crackling sequel to Rules of Prey, Twin Cities Sleuth Lucas Davenport teams up with NYPD Lieutenant Lily Rothenberg to track down an elusive killer, known only as Shadow Love. Among the victims are a Minneapolis slumlord, a judge from Oklahoma City, and a Manhattan politician. The murder weapon is a Native American ceremonial knife.