You can read the books in any order. Each is designed to be self-contained. Tolstoy says somewhere that our culture has a tendency to imagine that physical beauty has a moral equivalence - to think that beautiful people are good people. My criminal is a beautiful child who becomes a beautiful woman. Yet people find it hard to believe ill of her, simply because she is so beautiful.
Fiction is a wonderful medium for exploring how viewpoint can influence interpretation.
It's not what you see, it's the way that you see it. During the 1970s I had enjoyed Lawrence Durrell's Alexandra Quartet and Robertson Davies' Deptford Trilogy . I wanted to see it was possible to do something similar in crime fiction. The Four Last Things is told in the third person through the viewpoints of a male paedophile and a woman training to be an Anglican priest. The Judgement of Strangers is narrated in the first person by a sex-starved suburban vicar.