Cell Site Analysis – The importance of defence review

Cell Site Analysis is a technique used to determine which cells a mobile telephone is likely to connect to, given the features and behaviour of the mobile network at a particular geographical point or region of interest. We are regularly instructed to conduct Cell Site Analysis in cases that involve drugs and drugs supply and a key part of this work is the attribution of a phone involved in the supply of drugs (the ‘drugs phone’), generally comparing patterns of life with a phone known to be associated with your client (the ‘clean phone’). This comes from the common trait of keeping ‘business’ and personal separate, with two separate phones.

Common methods used to attribute a drugs phone to an individual include co-location of drugs phones and ‘clean’ phones, frequently used cells (showing areas frequently visited by the phone) and ‘bed and breakfast cells’ (helping establish where the phones are overnight, when the user is generally asleep). Despite how this analysis can be presented at times, these analyses are not conclusive in their own right and there are often several other unexplored lines of enquiry that can be overlooked by the Crown. 

The following casework example illustrates how expanding the scope of a Cell Site Assessment can significantly change alter the apparent evidence value of pre-existing findings.

Case Background

The client (Mr Y) had been charged with being concerned in the supply of drugs. One of his co-defendants (Mr Z) had already pleaded guilty and been sentenced to prison for the same offence, but Mr Y protested his innocence, and maintained that it was his friend, Mr Z, who was in control of the drugs phone.

Crown Evidence

All the Crown cell site evidence related only to Mr Y. As Mr Z had pleaded guilty at an early stage, the investigation did not include any cell site analysis surrounding his phone.

The Crown’s case rested on two main strands of evidence in order to attribute the drugs phone to Mr Y:

• The most frequently used cells for the drugs phone were found to cover Mr Y’s home address.
• There was significant co-location between the drugs phone and Mr Y’s personal phone.

The case was therefore made that Mr Y was in control of the drugs phone, as supported by it frequently being used in an area that included Mr Y’s home, and the drugs phone regularly being co-located with Mr Y.  So how compelling was the evidence to support this?

Our Recommendations

• Having reviewed the evidence, we recommended that the call data for Mr Z be obtained, as assessing this alongside the data of Mr Y would be key to the issues in the case. We also recommended analysis focus upon the following points, as the most probative analysis given the circumstances:
• Co-location analysis on the ‘drugs phone’ and Mr Y, with consideration of the location of Mr Z. It may well be the case that Mr Y’s phone and the drugs phone were in the same place at the same time, but the drugs phone may be in the possession of someone else - Mr Z for example.
• Non co-location analysis on the ‘drugs phone’ and Mr Y with consideration of the location of Mr Z. Whilst placing the phones together as part of establishing co-location is a critical aspect, it can be even more critical to consider the opposite – are the phones demonstrably apart at any time? 
• Analysis of locations of the ‘drugs phone’, Mr Y and Mr Z when bulk messages were sent. Bulk messages are one of the primary ways of ‘advertising’ drugs, by sending a message to all ‘business’ contacts. It is imperative that any analysis includes where the phones were at the time these messages were sent.

None of this analysis had been conducted by Crown; the need to consider competing hypotheses seemingly having been overlooked because results appeared to ‘fit’ the allegations.

Our Findings

Upon analysis, the key findings were:

• The majority of co-location between the ‘drugs phone’ and Mr Y takes place near the home addresses of both Mr Y and Mr Z.
• On every occasion when the ‘drugs phone’ and Mr Y were co-locating away from the home addresses, Mr Z is also operating in the same area. This supports Mr Y’s assertion that he would regularly spend time with Mr Z.
• Non co-location analysis identified that on 8 dates the ‘drugs phone’ and Mr Y were operating in different geographical location. This analysis identified that there were no occasions for Mr Z. In short, this demonstrated that that there were times where Mr Y and the ‘drugs phone’ were not together, yet no instances of Mr Z and the ‘drugs phone’ being apart.
• Numerous occasions of bulk texts sent out by the drugs phone were analysed. This identified that on only one occasion Mr Y was operating in a similar geographical area as the ‘drugs phone’ whereas Mr Z was operating in the same area on nine occasions.

Outcome

Our analysis showed that whilst the ‘drugs phone’ had used cells near to Mr Y’s home address the same was true in respect of Mr Z who lived close to Mr Y.  Additionally, whilst Mr Y regularly co-located with the ‘drugs phone’, there were times when he didn’t.  The same was not true in respect of Mr Z.  Overall, the findings were as might be expected if, as Mr Y had said, the ‘drugs phone’ was controlled by Mr Z.

As a result of our work no evidence was offered against Mr Y and not guilty verdicts were recorded. 

The nuances of every Cell Site case will be different, and whilst findings can seem compelling at first glance they may not be so after more detailed scrutiny.  Not only can existing findings be incorrectly interpreted, but as illustrated above an incomplete scope of work can lead to misleading conclusions. So next time you have a Cell Site case with seemingly compelling findings, get in touch with one of our Cell Site Analysts who will happily test the evidence for you to see if it stands up.