The Crime Writer's Guide to Police Practice and Procedure by Michael O'Byrne is an excellent guide to how the police forces work in the UK. Who will be first on the scene when a body is found? How is evidence collected? How are criminal investigations planned and managed?
Michael O’Byrne is a retired British police officer who rose from constable to chief constable (the highest rank), having worked in the Royal Hong Kong Police, the Metropolitan Police (including New Scotland Yard), Surrey, Thames Valley and Bedfordshire. He writes in plain English, from experience, with intelligence and humour. Even if you're not writing crime books, it’s an interesting read.
Here's the description:
The Crime Writers Guide to Police Practice and Procedure is the detective in your pocket - something you can reach for when you feel your writing needs that short sharp shock of real-life investigating. Every crime writer has paused at some key point in the development of their book to wonder about what happens in real life. How far from that can they safely go for the sake of the plot and still be believable? How does a cop react to a bloated body, or even worse a part of one? This well-crafted book has been written with this in mind. It can be what you want it to be; a handy reference book - how can I use low count DNA to identify the killer? - or a textbook to guide you at the outset whilst you are still developing your plot, leaving you confident that you have covered all the angles.
I’m currently writing slightly surreal comic murder mysteries in which a twenty-six-year-old amateur sleuth called Emily Castles solves the crime and saves the day, aided by her loveable side-kick, eccentric philosophy professor Dr. Muriel Crowther. The mysteries are set in present-day England and, as you can imagine, I want to keep the police out of these stories as far as possible, otherwise they would just seal off the area, bring in an investigative team, and solve the case themselves using their collective years of experience and expert resources.
But even though I’m not writing police procedurals, it’s helpful to understand who will turn up when a body is found, and what they will do next. I don’t have any friends or relatives in the police and have never been arrested or cautioned, and never been a victim of crime. The only contact I have had, on a professional level, was twenty-five years ago when I called the local police station to report that I had seen a man masturbating in an alleyway that was often used as a cut-through by schoolchildren. Lovely as it would be to turn up now at my local police station in Brixton and introduce myself as an author of mystery books, who is keen to be taken out for a ride in a squad car with the blue lights flashing so I can ask lots of intelligent questions, instead I can get the basics from this book - 'the detective in your pocket', as it is so aptly described in the blurb.
This book explains how British police forces interact with each other and with police forces overseas, what kind of information is available through Interpol, and why, the numbers of officers needed for investigations of serious crimes, how the depiction of the police on TV differs from the reality, some of the differences between UK and US policing, how evidence is gathered and stored, whether evidence gained illegally is permissible in court in the UK, and so on.
The author also gives us his views on professional profilers, tells us which crime writers he enjoys reading, and why, and also reflects on the cyclical nature of change in big organisations. He tells us whether a detective or a uniformed officer is more likely to vomit at the scene of a murder (the vomiting rookie cop is a common trope in TV police drama, of course), gives us a hint about which regional police force might be watching too much TV, and explains how HOLMES works (the police computer, not Britain's most famous fictional detective).
The book is matter-of-fact, credible and entertaining. Highly recommended.
The Crime Writer's Guide to Police Practice and Procedure is available in the US and the UK from all the usual online bookshops, or you can order it from your local independent bookshop.