Sharp Force by Patricia Cornwell

During the early hours of Christmas morning, chief medical examiner Dr Kay Scarpetta receives a chilling call. The Phantom Slasher has struck again. The serial killer has terrorised Northern Virginia for months. His pattern is to stalk with a sophisticated technology that enables him to invade his victims' homes and watch their every move. They wake up to a ghost-like hologram before being murdered in their beds. Scarpetta is summoned to Mercy Island, the site of a notorious psychiatric hospital where two people have been brutalised, one of them from Scarpetta's past. It soon becomes apparent that she could be next...