Why does Lepore continually return to Alphonso James Frye and his trial throughout the book over other events from Marston's younger days?

James Alphonso Frye was a black man accused of murder in Washington D.C. Marston used his trial as an opportunity to test his lie detection system in an effort to establish it as admissible evidence. This was unsuccessful and Frye, who maintained his innocence, spent 20 years in prison. Frye believes his lawyers, who were students of Marston, were more concerned with helping Marston than defending their client.