"If we can prove that he did it," the Federal prosecutor told the jury at Dr. MacDonald's murder trial, "then we don't need to prove that he's the kind of guy who could have done it." Both these questions are probed in Mr. McGinniss's "Fatal Vision," along with an obvious third question: If he did it, in God's name, why? It's a long, compelling story, with a cast approaching thousands…. (p. 12)

Dr. MacDonald's personality emerges in chapters of taped reminiscence inserted throughout the chronological narrative. At first, this device seems cumbersome. The time fluctuations become confusing, and Dr. MacDonald's sexual preoccupations constitute merely a pathetic and basically boring case of arrested adolescence. But as the story moves forward, the first-person counterpoint begins to sound much more significant, and eventually it adds to the book's impact. Other major figures are memorably sketched, especially the couple's parents. (pp. 12, 32)

But even...