What is the author's style in The Book of Evidence by John Banville?

Banville writes from the fractured mind of Frederick Montgomery. The language is often erratic in thought, as Montgomery switches from storytelling to his intruding thoughts to an analysis of what he has written. It is a personal journal, but it is intended to be Montgomery's own account to impress members of a court, the jury, the angry crowd and the media. Eventually, he settles for the account going in his official file. The investigating detective questions its accuracy.