Obsessed with True Crime discussion

I was adding Sherlock Holmes and the Autumn of Terror to the JTR shelf, but I can't decide whether to call it fictionalized or not. The author used Holmes's familiar techniques to solve the Jack the Ripper murders and he named a real suspect, backed it up with real evidence -- the whole ball of wax.

Here's the thing: he wrote the resulting book as if he WERE Sherlock Holmes.

Do I call this fictionalized or not?

Interesting.