Yes, the movie is based on journalist Mike Finkel's book "True Story: Murder, Memoir, Mea Culpa" - still, I don't like "True Story" as a title for the movie, it's too generic.  And even though it's a compelling and somewhat odd series of events coming together at the same time, it's not so unbelievable that you need to preface the fact that this is a 'true story'....