The murder mystery kept me interested but the writing needed a little elevation to make this book amazing. I was reading an early copy (ARC) so there are some issues I can look past but I was left with questions, and I don't think that was the author's intention. But maybe it was, and in that case, good job. 

One very specific issue I had reading this was the overuse of the word "belly". A character has a stab wound in the abdomen. This person, the doctor, the FBI agent and every other person who talks about it, calls it a cut in the belly. A medical professional would not say that. I doubt an FBI agent would either.  It felt wrong reading a variation of that phrase over and over. (I work in medicine and I only say "belly" when talking to my youngest patients).
Without getting into specifics too much, there were some other things that stood out to me. Details about time frames and motives mostly.