Apprehension - The John Kelly Series, #1

Good cop. Bad trouble. Kelly was a pro until his niece was murdered right before his eyes. His family says he failed her, but Kelly can't share his one shocking, buried-and criminal-act of vengeance. Now, fellow detectives digging into another case will find the evidence that can end Kelly's career and send him to prison. Kelly must focus on a pedophile trial to protect a child. It should be a slam dunk except the hotshot defense attorney is his new girlfriend, Rachel Cohen.
She has a secret too, one that will destroy Kelly on the stand. Will his friends, working in secret to save him, find the missing piece before he is forced to the breaking point?