One step up from that, we've got the minutiae of forensics, the laws of evidence etc. I like a little of this as a reader. The detail adds depth for me, but not everyone cares if my fictional detective is up on his powers of search and seizure. Lots of novels get this one very wrong, but most readers won't notice. One reason I haven't set a novel outside the UK is that getting to grip with another jurisdictions laws would be a lot of work for a relatively small reward.
As Stephen C Spencer put it, a novel should entertain, amuse and educate. Two out of three ain't bad, but you've got to go three for three if you want a real winner. A little insight into criminology, psychology, pathology and law adds a layer. It's also very time consuming to get right. I've had emails about very specific items like the effect of a tidal river on a body. I'll be honest, I have massaged the science a little. Most readers don't want to know exactly how fatty acid ethyl esters in the liver and adipose tissue can be used as a way of determining if the dead guy had been drinking. I think it's fascinating, but brevity often demands the detail is edited out. How the cops determine something like this is much less important than the mere fact that they can, and do, figure it out.
The other issue is how gritty to be. For sensitive issues like kidnap, rape or vulnerable victims there is a delicate balance to strike between accuracy and decency. If the reader is too offended they may stop reading. Sometimes this is great marketing technique as it does polarise opinion and get people talking, but that is definitely a gamble I'd prefer to avoid.
I often borrow elements of real cases. Many books give psychological profiles for killers, and keeping fictional characters consistent so that they would show the same indicators of psychopathy is a great way to ensure they are believable. These profiles often give a great deal of insight into the nature versus nurture debate among criminologists. Are killers born, or made? Women often kill in a more passive manner via poison. Men err towards the confrontational and therefore violent.
With Dead on Demand, we didn't explore this sort of background as much as I'd have liked. It was action packed, with something happening on pretty much every page. It was a whirlwind of a tale, much like the challenge that saw us write it.
For book two, we're aiming for a little more light and shade. Not just when when, where, who and how but more of the why. We think we did OK on the former, particularly the how (which was, despite my disregard for the finer points of pathology) pretty much on the money. Getting inside the minds of the victims is something we'd like to explore a little more. For that reason, I'm going to be using external consults with a psychologist as well as police, forensic and entymological experts for the return of David Morton. The general outline is done in principle, but we aren't rushing this one. We will release sometime in 2013, but we'd like to deliver the best story we can at a fair price.