Law Enforcement Case Study - Drugs / "Clean & Dirty" phone - Cell Site Analysis

The following is an anonymised case study based on a real assignment conducted by CCL-Forensics for a Law Enforcement Agency

Many criminals will use two mobile phones: known as their “clean” and “dirty” phones.  The clean phone is their everyday phone used for legitimate means.  The dirty phone is used for the commission of crime.  Cell Site Analysis is useful in proving that these two phones were travelling together, hence attributing an individual to a phone used in criminality.

In this example, police raided a number of premises as part of an investigation into large scale organised drug dealing.  A number of mobile phones were seized, the contents of which were subsequently analysed.  This showed a handful of common phone numbers which were either called by, or called, the seized phones.  However, the phones bearing those numbers of interest were not found during the raids and it was unknown at that time to whom they may belong.

Police obtained the call data records for those phone numbers and carried out some preliminary analysis of the data to understand where they could have been used.  Some of the areas were relevant to the case – others not.

Some time later, police were given a name of a potential suspect in the case, and the enquiry took a different direction.  As part of this, his mobile phone was examined and the call data records obtained.

The police called in CCL-Forensics Cell Site Experts, who analysed the call data from the suspect’s phone in conjunction with the data records already obtained.  The aim was to analyse whether the phones were moving together with the suspect’s legitimate phone.

They paid particular attention to the patterns of usage – where phones were used first thing in the morning and last thing at night.  They also analysed the location in relation to the suspect’s workplace, home address and other notable locations in the investigation.

By carrying out measurements at all these locations, it was possible to assess the movement and areas of common usage of the phones which were prevalent in communication about the drugs operation.

In addition, CCL-Forensics was able to take concerns raised by the defence cell site expert, and prove scientifically that their claims were not valid.