The Investigation

From first page Avon paperback July 1976:

Into an unearthly sequence of events, in which dead bodies seem to resurrect themselves without cause, comes Harvey Sciss, the statistical mastermind who, in his brilliantly offbeat way, discerns a pattern in the gruesome incidents. Ironically, Sciss himself becomes the prime suspect as even wild animals and alien invaders are under investigation in a case that stretches to the utmost limits the elastic faculties of human reason.