Cell Site Analysis in Modern Criminal Investigations

26 July 2024

Cell site analysis has emerged as a pivotal technique in criminal investigations, offering invaluable insights into the movements and communications of suspects.

A Senior Cell Site Analyst at IntaForensics, recently presented a comprehensive CPD webinar highlighting the benefits and limitations of cell site analysis. This article explores the key points from the presentation, providing an expert overview for those interested in the intricacies of this forensic communications method.

Understanding Cell Site Analysis

Cell site analysis involves the forensic examination of mobile phone data to identify a geographic location of a device at a specific time. This process leverages Call Data Records (CDRs) provided by mobile network operators, which include details such as cell ID, date, time, and duration of communications. When a mobile device engages in activities like calls, texts, or data sessions, these interactions are logged, enabling analysts to consider the device’s movements.

The Basics of Mobile Communications

Mobile devices communicate via radio waves, which transmit and receive signals to and from a network of base stations, often referred to as cell towers or masts. These masts support the radio antennas necessary for facilitating mobile communications. The antennas are typically positioned high up to minimise obstructions, allowing signals to travel with fewer interruptions. Much like beams of light from a lighthouse, radio waves can be obstructed by physical barriers such as buildings, hills, or dense foliage, affecting communication quality.

Key Components of Cell Site Analysis

Our cell site expert explains that cell site analysis typically involves three main components:

1. Call Data Record (CDR) Analysis: This involves examining patterns of usage, identifying the most frequently used cells, and determining common contacts and the frequency of communication. This analysis helps in understanding the routine and movements of the device.

2. Cell Site Location Comparison: This step involves comparing the locations of cell sites with known locations of interest in the investigation. It helps in establishing whether a device could have been in proximity to significant locations at relevant times.

3. Radio Frequency Propagation Surveys (RF Surveys): Conducting RF surveys involves measuring the radio signal strength and coverage area of cell sites. These surveys validate whether the cells appearing in CDRs provide service to the locations of interest. They are crucial in cases where precise geographic validation is necessary.

These elements can be combined to build a robust picture of a device’s activity, although some cases might not require a survey, relying instead on the analyst’s expertise to form an opinion based on existing data.

Cell Site Analysis - Combine Call Data Records

An example of call data records in a combined schedule.

Practical Applications and Case Studies

The theoretical understanding of cell site analysis is crucial, but its practical applications in real-life investigations truly highlight its value. By examining detailed case studies, we can appreciate how this technique has been instrumental in solving complex criminal cases. Cell site analysis supports investigations but also plays a decisive role in court proceedings. These case studies demonstrate the versatility and effectiveness of cell site analysis in different legal contexts, ranging from violent crimes to intricate drug conspiracies.

Operation Cooper

Operation Cooper involved two sexual assault incidents in August and November 2022. The offender posed as a taxi driver to lure victims into his vehicle, where they were drugged and assaulted. Analysis of the offender’s mobile phone data, overlaid with CCTV footage and victims’ iOS location data, played a critical role in the investigation.

The cell site analysis involved matching the suspect’s call data with the locations captured on CCTV. Additionally, RF survey measurements showed that the cell IDs used by the suspect’s phone provided service along the route taken by the vehicle. The data correlated with the time and place of the incidents. The comprehensive analysis led to a conviction, demonstrating the power of integrating mobile data with other forms of evidence.

R v Defendant

In this case, the investigation centred around conspiracy to supply Class A drugs and modern slavery offences. IntaForensics was instructed by the defence to review the prosecution’s material and conduct RF surveys at two locations of interest. The primary challenge was to determine who controlled the device identified as a ‘drugs line.’

The analysis revealed significant flaws in the prosecution’s data. Key issues included the lack of detailed cell IDs and azimuth data, which are critical for accurate interpretation of the data. Moreover, the prosecution had not considered non-co-location evidence, which could indicate times when the devices were not together. The careful examination and expert testimony by IntaForensics led the Crown Prosecution Service (CPS) to offer no evidence, resulting in the case’s dismissal.

Operation Code Minister

This case was a law enforcement agency investigation into a large-scale conspiracy to supply controlled drugs. The suspects used the now-defunct encrypted communication platform EncroChat. The analysis was extensive, covering surveillance observations, Automatic Number Plate Recognition (ANPR) activations, and GPS data from vehicles. IntaForensics conducted attribution analysis for multiple devices at various home addresses.

The RF surveys were crucial in determining whether the devices could have been used by the defendants at the relevant times and places in question. The comprehensive analysis and expert witness testimony provided by IntaForensics supported the prosecution, leading to convictions and custodial sentences for the defendants.

Limitations of Cell Site Analysis

Despite its effectiveness, cell site analysis has inherent limitations that must be acknowledged to ensure accurate interpretation of the data. These limitations include:

1. Lack of Communication Content: Cell site analysis cannot provide the content of communications. It can reveal when and where a communication occurred but not what was said or typed. This limitation means that while the technique can show that a phone was used, it cannot specify the nature of the conversation or message.

2. Precision of Location: While cell site analysis can indicate a general area where a device was located, it cannot pinpoint the exact location with high precision. This means it can show that a device was in a certain neighbourhood but not the specific building or room.

3. User Identification: The analysis cannot determine who was using the device at the time of the communication. It can only suggest that a particular device was active, not who had it in their possession. This is where attribution analysis, combined with other evidence types such as CCTV, can support in suggesting the identification of a user.

3. Data Event Timings: The timing of data events, such as data sessions, can be misleading. Data sessions may last for hours and include multiple interactions, not necessarily aligned with the timestamps provided. This discrepancy requires careful expert analysis to avoid incorrect conclusions.

Regulatory Changes and Future Considerations

The field of cell site analysis is continuously evolving, with new regulatory standards introduced by the Forensic Science Regulator (FSR). As of October 2, 2023, forensic units must achieve UKAS accreditation to ISO/IEC 17025:2017 standards within 24 months. This move ensures that all forensic analysis adheres to high scientific quality and compliance standards, reflecting the FSR’s commitment to maintaining rigorous forensic standards across the criminal justice system.

At IntaForensics, we are the first and only organisation to be granted accreditation to ISO/IEC 17025:2017 and the Forensic Science Regulator’s Codes of Practice and Conduct for cell site analysis.

Impact of Regulatory Changes

These regulatory changes will significantly impact how cell site analysis is conducted and presented in court. The requirement for accreditation ensures that all analysis is performed to a high standard, increasing the reliability and credibility of the evidence. This change is particularly important in complex cases where precise and accurate data interpretation can be the difference between conviction and acquittal.

The Future of Cell Site Analysis

Looking ahead, several key trends and developments are expected to shape the future of cell site analysis:

1. Phasing out 2G and 3G Technology: All UK network providers plan to withdraw 2G and 3G technology by 2033. 3G has already been turned off by EE and Vodafone in early 2024, Three expect to do the same by the end of the year, with O2 following in 2025. The network providers are reusing the frequencies for 4G and 5G services. This shift will affect historic cases, as older data may become less accessible. Experts will need to adapt their methods and potentially rely more on opinion-based analysis.

2. Advances in Technology: As mobile technology advances, new methods of data collection and analysis will emerge. This will likely include more sophisticated tracking techniques and improved accuracy in location data, enhancing the overall effectiveness of cell site analysis.

3. 5G standalone services: These services are being increasingly deployed and plans for 6G are already on the horizon in this ever-changing landscape.

Conclusion

Cell site analysis remains a cornerstone of modern forensic investigations, offering critical insights into criminal activities. The expertise of analysts and adherence to stringent regulatory standards ensure that this technique continues to support the pursuit of justice effectively. By understanding both the capabilities and limitations of cell site analysis, legal professionals can better leverage this powerful tool in their cases.

For any queries or further information, IntaForensics encourages direct contact with their skilled team of analysts. Their expertise and commitment to high standards make them a valuable resource in the ever-evolving landscape of digital forensics.

By embracing the latest technologies and adhering to rigorous standards, cell site analysis will continue to play a vital role in modern criminal investigations, helping to ensure that justice is served based on reliable and accurate evidence.

For more information, get in touch with our experts at IntaForensics to find out how they can use cell site analysis and call data records to support your criminal investigation or defence strategy.

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