Since I was a kid, disappointed that Agatha Christie mysteries were written so as not to be predictable in advance, I wanted to read a mystery series where at the end of each chapter, there's always enough clues to predict who the murderer is. But it's very, very hard after the 1st chapter, a little bit easier after the 2nd chapter, etc. That's good mystery writing, in my opinion. Not creating a solution in the last few paragraphs that's impossible to predict in advance, because its not grounded in any of the prior clues.