The Jigsaw Puzzle Murders

Detective Frank Lombardi has risen from Police officer to Detective rather fast in his career. His life seems to be going pretty well living the carefree lifestyle until a case becomes personal. The serial killer is addressing his victims that have crossed Frank's interesting life. Using a envelope holding puzzle pieces that form a picture of the last time Frank saw the victim alive. With each completed puzzle there is one left. What does this new puzzle form? Could it be Frank as the last victim? Could it be the killer? Now that is the mystery and why is this happening now? The storyline has many characters that come and go out of the story making it full of twists and turns.