What are the motifs in The Book of Evidence by John Banville?

Psychological anomalies is a recurring idea. Montgomery's narcissism is evident from the first page of The Book of Evidence. He can only detail things that put him in the best light. That is not to say that he can't say mean things about himself, because those things may bring him the most attention. He is pompous in thinking that he would be able to narrate to the court in such detail. He is angry when the police pare down his statement to the reality of him cold-bloodedly murdering a young and helpless girl.