Is Karin Slaughter always this long-winded? At 436 pages, her 12th novel, Criminal, reads about 150 pages too many, and in several passages, it becomes painfully clear that Slaughter has jammed into the narrative every scrap of research she could drag up on subjects that might not deserve such scrupulous examination. Not that the garrulousness means readers should ignore Criminal. Even when Slaughter is way too wordy, she’s still entirely readable.

As with earlier novels, Criminal takes place in Slaughter’s native Georgia, specifically in Atlanta. The action covers two alternating time periods, 1974-75 and the present. The two are connected by the plot and by a handful of characters. All of the latter fall into one of three categories: members of the Atlanta Police Department and the Georgia Bureau of Investigation; murder victims, mostly young prostitutes; and, the smallest and most tantalizing category, the killer, a spectacularly heinous fellow who isn’t conclusively identified until very late in the book.

Out of this mix, it’s a cop named Amanda Wagner who holds the plot on course. In the book’s 1970s passages, she’s a rookie APD officer with an intuitively sharp sleuthing touch. Amanda also carries the burden of a bullying father who happens to be a senior member of both the Atlanta cops and the Ku Klux Klan. Forty years later, having survived daddy, Amanda is a 60ish senior officer with the GBI. Her investigative instincts remain intact, but she’s added an intellectual rationale for her policing moves. That, and a gift for keeping secrets, make her essential in assuring that Slaughter’s scattergun approach to the narrative produces a reasonably coherent resolution.

Still, Slaughter’s insistence on sharing with readers her massive research stands as a barrier against total enjoyment of Criminal. The author’s Acknowledgments let us know we’re in for a history of the Atlanta Police Department, but did we need whole chapters to convince us that the ATP of the 1970s may have been the most racist and sexist organization in the history of policing?

True enough, one intriguing nugget of irony emerges from the ton of Atlanta cop research. When Amanda Wagner’s daddy sends his KKK robes to the dry cleaner’s shop for laundering, who restores them to their pristine white? Answer: the shop’s black employees.