In Conan Doyle for the Defense: The True Story of a Sensational British Murder, a Quest for Justice, and the World’s Most Famous Detective Writer (Random House, June), Fox revisits the real-life sleuthing of Arthur Conan Doyle.

What triggered your interest in this case?

Thirty years ago when I first moved to New York, I was reading John Dickson Carr’s Conan Doyle biography on my way to work. Just in passing, he mentioned Conan Doyle helped right a wrongful conviction in a murder case. I almost dropped the book in the middle of the A train. I thought, the creator of Sherlock Holmes was involved in investigating a real murder? Why isn’t this more widely known? I filed it away in the back of my brain.

Did you uncover anything that previous Conan Doyle biographers missed?

The whole case! Every Conan Doyle bio—and there are dozens—has anywhere from a paragraph to a chapter on the Oscar Slater case, but there are no freestanding books, at least not on this side of the Atlantic. When I went to search archives in Edinburgh and Glasgow, I literally got thousands of pages of documents. It took me about a year and a half to go through all that material. It’s a story that no existing biography has been able to tell because it really does occupy a book by itself.

Did focusing on a single episode in the life of Conan Doyle yield any surprising insight into the man himself?

I was absolutely thrilled and delighted to learn more about Conan Doyle the crusader. He was one of the most prominent men in public life in Britain in his day, and he lived till 1930. So he spent a long time doing what we now might call activism and for very humanist causes. Here he is championing a man he clearly found personally distasteful, because Conan Doyle conducted himself as an upright Victorian and truly lived by those values. But he also was so horrified by this gross miscarriage of justice and gross framing of an innocent man that he brought all his brain power and all of his renown to bear on getting Oscar Slater freed.

How does this story resonate today?

This is about one man being framed for a crime he didn’t commit. The larger story is about the construction of the Other. It’s a story about a society that took out its roiling, nebulous, subconscious fears and bound them up with ethnicity, religion, nationality. And, of course, all of the things that were done to Oscar Slater in the early decades of the 20th century, tarring him with the reputation of a criminal and framing him for a crime that literally within a week the police and prosecutors knew he was innocent of, all of that is done today. The only thing that has changed is that we now have a name for this phenomenon—we call it “profiling.”