Technicalities in Under a Silent Moon

I had a lovely review on from a Vine program participant (Gail Rodgers, if you’re reading, thank you very much! And thank you to everyone else who’s left me a review on Amazon, I never get to say thank you but I appreciate each and every one of you) for Under a Silent Moon. The reviewer mentioned some of the procedural aspects of Under a Silent Moon and that these are not fully explained.

This is absolutely true. And although I did consider putting in some sort of glossary, it felt as if that would break the fourth wall somewhat and remind the reader that you’re not actually reading an account of a crime, you’re reading a book. I know you ARE reading a book, but I like to pretend it’s all real…

(I did actually do a ‘cast of characters’ for the US edition, as there are a lot of individuals to keep track of, but I disguised it as an email from the Head of Department listing the personnel involved in the case.)

Nevertheless, there are some aspects of the procedure that might warrant further explanation, and that’s something I can do here without giving away any of the plot. I’ll do this as a Q&A – and if, after reading Under a Silent Moon, you think of anything else that you’d like explained, please do leave me a note and I will be delighted to respond!

Brace yourselves, people, this could get technical…


What is a ‘nominal’?

A nominal is a person who is known to the police. This doesn’t necessarily mean they are a suspect – the term encompasses witnesses, suspects, offenders and even victims. A nominal is someone who appears on the database and therefore has a nominal record, along with a URN (unique reference number). I have left the URNs out of Under a Silent Moon because there are enough numbers in the book as it is – but everyone on the system will have a number, making them easy to look up on the database. You may notice that the police officers in my books don’t often use the term ‘suspect’ even when you might think that would be the best term to use. The reason for this is that once someone becomes a suspect you have to treat them differently – everything becomes very official. (Thanks to my lovely friend Lisa for explaining the differences to me!)

Of course, someone can be more than one thing: you can be a nominal and a witness, then later you might be a suspect and eventually following a successful prosecution you can become an offender.


What is a ‘5x5x5’?

A 5x5x5 (colloquially known as a ‘five by five’) is an intelligence report. The name comes from the system of grading the intelligence, since it gets three scores: firstly it’s scored by the reliability of the source, from A-E, then by the accuracy of the intelligence contained within it, from 1-5, and finally who is allowed to receive the report, again 1-5. You can read more about the 5x5x5 and its grading system here, but for now I’ll just give you an example. You will see that many of my 5x5x5s in Under a Silent Moon are graded B/2/4.  This means the source is ‘mostly reliable’ (B – you only get an ‘A’ these days for physical evidence, eg a DNA match), the intelligence is ‘known personally to source but not to officer’ (2 – ie, should be accurate if you trust your source), and that the intelligence report should only be shared within the originating agency only, in this case the fictional Eden Police Service (4). Another example might be if you, as an officer, received a tip-off regarding a known nominal from a member of the public while you were out on patrol. If you didn’t know the person who spoke to you, this might be recorded as E/4/1 – an untested source (E), quality of the information cannot be judged (4), and may be disseminated to other agencies (1) – for example, social services or the UK Border Agency.

Intelligence analysis (the job I used to do) revolves around the 5x5x5. There is plenty more to it, of course, but the primary function of the role is to keep up to date with the intelligence regarding the cases you are working on, collate reports, look for patterns and cross reference them with crime data.

The 5x5x5 intelligence system is governed by the Regulation of Investigatory Powers Act 2000 (known as RIPA). Part of RIPA (Part II, if you’re interested) covers covert human intelligence sources (CHIS – another acronym for you). In the past, a police officer used to make use of what was cosily called a ‘snout’ or a ‘grass’ – someone of a dubious criminal background who would meet up with the officer and provide them with information in exchange for a cup of tea, or a packet of fags (cigarettes) or cash, or even possibly a ‘turning a blind eye’ to their own, presumably less serious, criminal proclivities. You will have seen numerous police dramas where cases are solved because of a copper’s ‘nose’, or ‘gut instinct’ – in other words, they have received a tip-off from their ‘snout’ and will act upon it to gather evidence and get someone locked away. RIPA was supposed to put an end to all of that, and a good thing too – because it put people in an incredibly vulnerable position, both police officers who put their trust and their career in the hands of someone who had all manner of things to lose and gain by the information they supplied, and also might be known to ‘lean on’ their snouts; and those supplying the information, who had no real rights or protection from prosecution or from repercussions from the criminals they’d betrayed. These days, the CHIS (covert human intelligence source, ie the person who has information to share) is ‘managed’ by a source handler, a dedicated officer who collects the intelligence and protects the source. The intelligence is then graded (eg B/2/1 as above), sanitised (to remove any reference that might identify the source, for example), recorded on a searchable intelligence database and disseminated to individuals authorised to view it, for whom the intelligence is relevant (eg, the analyst!)


What are ‘billings’ and ‘cell site data’?

You can read a really good summary of all that phone stuff here. For the purposes of the book, though, let me explain the analysis that assists with an investigation. If the police have a phone number (let’s stick to mobile phones, here, but the same is true of landlines) they can request from the phone’s service provider three things using a very long and complicated online warrant form that goes into great detail of why the data is needed and which legislation permits it: billings, subscription data and cellsite data.

The billing is basically a mobile phone bill (without the cost) – a list of all the contacts made by the phone, dates, times and durations, including incoming and outgoing calls, SMS or text messages and MMS or multimedia messages. The application must be for a relevant period of time, for example for a month either side of an offence that’s being investigated. This will usually be presented as a spreadsheet of very basic data which the analyst will then have to clean up. You can learn a lot of useful things from a phone billing – starting with the most frequently contacted other numbers. Here’s a really good basic summary of how analysts conduct telephone frequency analysis.

The subscription data amounts to the registration details of the phone. Often this will come back as ‘pay as you go, no subscriber’ because the user has bought the phone in a supermarket and never bothered to register it because they buy top ups in a shop rather than online. Contract phones are registered, and the owner’s details will then be provided.

The cellsite data is requested from the service provider as an ‘extra’, and will consist of a column added to the billing to show the nearest phone mast to the phone in question when each contact was made. Whilst this data is not really used for evidence, because phone masts can be spread far apart and the data isn’t always accurate (as anyone in the South East of England will know when their phone triggers a mast in France), it can be used to support other evidence, for example ANPR data (see below), or witness statements. It’s also useful to help identify the user of the phone, as the cellsite data will give an idea of where they live – since the first calls of the day and the last calls at night will probably be made from home.


Why do you only refer to the last three numbers of the phone number? And why do you refer to the number rather than the person?

It is very difficult, if not impossible, to prove that one person made a call to another person. What you can prove using phone data is that one phone contacted another phone. You can attribute the phone to a user, for example by subscription data – this person is the registered user of this phone – or by other means, for example a witness saw this person making a call shortly before they were arrested and their phone seized. You can have CCTV showing a person making a call on their mobile, which ties in with a record on the phone data provided by the service provider, but even so you would not state on your phone analysis that the person in question made the call.  Without corroborative evidence, all your suspect needs to say is that they loaned their phone to a person in the street, or they lost it, or sold it – and then your data is of no evidential use at all.

Because of the danger of assuming that an individual made a call, the police will always refer to the phone number rather than the user. And phone numbers are long and complicated to remember, so often the last three numbers will be used to identify the phone for the purposes of discussion and consideration.

Analysts provide something called an ‘Attribution List’ which is basically a table showing phone numbers relevant to the investigation, who it is believed is using that particular phone, and where to find the intelligence corroborating that belief. I am hoping to include an attribution list in the next Lou Smith book (for the time being, I’m using it myself to keep track of all the phones!


(For my purposes, too, I have tried to use numbers that won’t actually link back to a real phone. Obviously, when only mentioning the last three digits, this isn’t a worry – but where I have used the whole phone number, I have obtained it from this website, which allows you to look up who the service provider is, and, in the case of landlines, where the nearest telephone exchange is located. At the time of writing, all the mobile phone codes I have used are listed as not currently in use. Let’s hope they stay that way for a while, eh?)


What is ANPR data?

ANPR stands for Automatic Number Plate Recognition. This has been used in the UK for some time now, for everything from enforcing traffic speed limits (sending you an automatic speeding ticket in the post) to enabling ticketless car parking. ANPR cameras are also used for investigating crime. They can track stolen vehicles and identify cars that are untaxed or uninsured. Officers (and analysts) only have access to the data if it is required by their role, and for most investigations only the past 90 days’ worth of data is searchable – additional approval by a senior officer is required for anything older than that.


That’s all I can think of for now – please do ask me questions, if I can answer them here, I will. If you ask a question that might give something away about the book, I may reply privately so as not to spoil things for someone else.


  1. Hi Elizabeth
    Ah the good old police jargon. Being a police officer myself, I know it well. I am currently writing fiction, a crime thriller with a paranormal twist. I admit I struggle to have to explain the terms as to me it looks so much better to just go with it. I tend to overcome it by explaining it once and then using the acronyms after that. I agree with what you said about reviews, I don’t tend to respond on Amazon but every now and again I will send out a great big thank you on Facebook or Twitter and do a book giveaway for the paperback edition for my lovely followers. A positive review is like a virtual hug, I love them. 🙂
    Anyway well done with the book, it’s been great to follow your well deserved success. I admit I haven’t read this book yet but am planning to, when I get through my current reading list!

  2. Hi Elizabeth. I am waiting patiently for your new book to come out in Ottawa, Canada. I contacted a few stores and can’t seem to get a date. Any idea on which date it is coming out ? just waiting to rush to the store…..

  3. I’m on page 244, and it’s so good I don’t even want to finish- but I can’t stop reading! Hoping Lou Smith is going to be a series? And wondering why the 40 page novella on is not available in the US? Hopefully you’re doing lots of writing- I love all of your books!

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