The Names of Angels

S5, E3: The police investigate a series of rapes and murder of young, professional women in the Bradford area. After attacking them, he dresses the victim in a previous victims clothes and leaves their ID on the body. As the investigation continues, they learn from DNA that the man is responsible for at least seven murders over the years, but that he has never been arrested and as such, are unable to identify him. In a separate case, a former patient who has run away from his care home, Jack, contacts Tony. As a child, Jack killed his family and the police are concerned that he may lash out again.