Hello, Darkness: Jesse Ball's Silence Once Begun

Jesse Ball's novel Silence Once Begun seems to be playing on the border of fiction and creative nonfiction, for lack of a better term - his author's note at the outset says that the events in this novel are partially true. He structures the novel, at least the first part, as an investigation - reminds me of some Latin American fiction I've read, particularly novel by Patricio Pron; in this case, the narrator, named Jesse Ball, begins by stating that his wife at one point in their marriage suddenly stopped speaking for no apparent reason, which lead him to investigate another case of willed silence, which occurred in 1977 in Japan (not sure how much of this if any is true): the case he investigates involves a young man, Oda Satsuko (?), who for some completely inexplicable reason gets involved w/ some rough characters, loses a bet, and the consequence is he agrees to sign a confession - confessing to be a mass murderer wanted for death of 11 elderly people in his small city; why anyone would make such a bet (never stated why or what would happen if he won the bet) or why he would sign such a document under any circumstances or why a confession w/ no corroborating evidence at all would lead to imprisonment or what connection the guy who made the bet w/ him may have had with the murders - these are left completely unexamined, so the novel is kind of eccentric and uneven, to put it mildly. The investigation chapters are transcripts of prison interview that Ball has obtained, transcripts of his own interviews w/ various members of Oda's family, and news reports on his trial. The main point of the interviews is that Oda refused - other than a few words to one of his siblings protesting his innocence - to speak at all during any of the interviews or interrogations, he just let the case move forward. The mystery is: why? Some form of trauma or underlying mental illness? But wouldn't the authorities have had some interest in getting to the truth of the matter rather than prosecuting someone so obviously disturbed - again, w/ no corroborating evidence? I'm about a third of the way through this short novel; what will determine whether it's a really good novel is what connections Ball is able to make between the Oda case and the sorrow of his own, or the narrator's own if you prefer, life.