1st to die. James Patterson. 2001.

As the only woman homicide inspector in San Fransisco, Lindsay Boxer has to be tough. But nothing has prepared her for the honeymoon murders. 

A brutal maniac begins a killing spree - slaughtering newlywed couples - and Lindsay takes on the case. She is sickened by the deaths, but her determination to bring the murderer to justice is threatened by a personal tragedy. So she turns to Claire, a coroner, Cindy, a journalist, and Jill, an attorney, for help with both crises: and the Women’s Murder Club is born.