Praying For Sleep by Jeffery Deaver

Michael Hrubek, a young schizophrenic, has escaped from a hospital for the criminally insane.  And he's making his way towards Lis Atcheson, the teacher who testified at his murder trial.

Four people race to intercept him before he reaches her.  His psychiatrist, the hospital director, a profossional tracker.  And Lis's husband, who must get to Hrubek before the madman reaches his wife.

But Michael's mind - with its delusions of murder and betrayal - is crystal clear about one thing.  He knows Lis better than she knows herself.  And he carries with him a monstrous secret that will tear apart many lives during the course of this single horrifying night.