Conspiracy in Death by J.D. Robb

It was always a shock, not the hard one Bowers had hoped for. Eve had seen too much for that. But what one human could do to another was never routine for her. With the precision of a surgeon, a serial killer preys on the most vulnerable of souls of the world's city streets. The first victim: a homeless person, found dead in New York City. No bruises, no signs of a struggle. Just a laser-perfect, fist-sized hole where his heart had once been. Detective Eve Dallas is assigned to investigate. But as she is lured in to a cat-and-mouse game with the killer, Dallas also becomes the focus of an internal investigation. In her mind, Eve feels she has done nothing except irritate some fellow cops with connections in high places. But her struggle to bring a murderer to justice is about to be hindered by the fight to save her career