Sins of the Past — Julia Derek

Stay-at-home mom Kate Martinez's life is turned upside down when her husband Diego is stabbed to death, leaving her with no means to support their toddlers. Detectives Cooper and White are put on the case, and their only lead is the unusual knife left at the crime scene. Kate insists neither Diego nor she have any enemies.It turns out that Diego may have more enemies than Kate thinks; he was once a member of a vicious gang and kept this from Kate. When Kate discovers Diego's lies, she's devastated and turns to Trevor, a man she once dated who's now a friend.Little does she know that Trevor, too, used to be a member of a brutal gang--which happens to be a rival to her husband's gang. Has the past caught up with Diego, or is there a more sinister reason to his death? When Kate learns the truth, it may be too late...

NOTE: SINS OF THE PAST is the first book in the Cooper and White murder mystery series. It's more a WHYdunnit than a WHOdunnit. It has no explicit sex and little violence.