Watch your back. Karen Rose. 2013.

 Baltimore Homicide Detective Stevie Mazzetti has suffered losses no woman should have to endure. And, despite it all, she’s still a fighter. When she learns that her ex-partner might have miscarried justice, she’s determined to put the past to rights, even when she becomes a target.
 
It’s former Marine Clay Maynard’s job to see the risk in every situation, but he doesn’t have to look hard to find the danger surrounding Stevie. Since the minute he first saw her, Clay has wanted to protect the wounded officer, and he started loving her not long after that. So when Stevie attracts the attention of a vicious psychopath, Clay will do whatever it takes to keep her alive. That is, if he can stay ahead of a killer with everything to lose—and something terrifying to hide…