In Reasonable Doubt, Peter Manso explores a Cape Cod murder with unintended consequences for himself.

In a Boston Globe article on the trial of Chris McCowen for the 2002 murder of Christa Worthington on Cape Cod, a Harvard professor said that you'd chosen sides, bringing into question your objectivity. Do you agree?

I certainly won't cede the point to my enemies that I lost my balance or my perspective. There's no question, however, that fairly early on I chose sides. But I would maintain that choosing sides does not blind one to one's obligations as a journalist and as a historian. Anything I came up with in the course of... writing this book—or rather, in the course of my becoming a de facto member of the defense team—was shared with the other side. Which is a hell of a lot more than I can say for the prosecution.

What role did race play in Chris McCowen's trial?

I think you're on solid ground if you assume that if a black man is on trial for raping and murdering a white woman, race is going to enter into it. Does that mean absolutely that a black guy cannot get a fair trial? It does not. I thought the Cape [where Manso lives] was immune to racism. Dumb me. Shortly after the trial, three jurors filed affidavits claiming racism interfered with their verdict.

At what point did you realize that the project was moving from a murder investigation to an exposé of the corruption of justice?

As I began reading the discovery material—15 running feet of loose-leaf binders plus 4,000 or 5,000 pages of trial transcript—a very strange picture of "my" Cape Cod emerged: an incestuous, ingrown culture where judges go on vacation with prosecutors, and trial lawyers make huge donations to re-election campaigns. I began to smell a rat.... The book broadened into what's happened on Cape Cod in the last 25 years. Issues of racism, police misconduct, and crime on the Cape became a subtext of the trial proper. The book is less concerned in proving who killed Christa than it is with examining what goes into the trial of a black man in America today.

Cape Cod DA Michael O'Keefe indicted you in 2008—though the charges were dropped—of five felonies stemming from expired gun permits. How did that affect your work?

One of the most measurable effects was that it put an end to my going to prison and interviewing the defendant... the man who's at the center of my book. That speaks for itself. Who would dispute the idea that O'Keefe's indictment of me did not [sic] impact my book and was not [sic] a First Amendment issue? It's cost me at least a year in terms of finishing the book. I'm still in debt and probably will be for some time to come... not only because it took me much longer than it was supposed to but because of legal expenses. Thank God I had good lawyers who stood by me.