Witches of Three: Charlene (Witches of Three Series, #2) by Temple Hogan

As the middle sister of three witches, Police Officer Charlie Spencer has learned to be independent and go her own way. But now, she’s fallen for her handsome police captain, Nick Hilliard, and nothing is the same.

Between dodging bullets and trying to find a killer, Nick and Charlie are hard put to plan a life together. And will Nick accept the fact he’s in love with a witch?