Scientific Working Group on Digital Evidence (SWGDE) Continues to be Wrong - Mobile Forensics

SWGDE just updated their document "Recommendations for Cell Site Analysis History" in March 2025. They continue to be wrong and biased towards law enforcement and prosecutors. It's not unexpected as over 90% of the membership is law enforcement.

I am a mobile forensics expert and a cellular network technology expert. I have worked in cellular testing and technology for over 30 years.

The following is taken from the September 25, 2017 SWGDE document “Recommendations for Cell Site Analysis”.

from SWGDE Recommendations for Cell Site Analysis History - 2017

The following is taken from the March 3, 2025 SWGDE document “Recommendations for Historical Cell Site Analysis”.

from Recommendations for Historical Cell Site Analysis - 2025

The first thing is they continue to be wrong about their logic and reasoning for the plotting of the range or distance from the cell. It is true that the historical records provided by the network operators typically have a column for the distance to the cell or phone. However, SWGDE says that the latitude longitude estimate should not be used due to proprietary algorithms (they got that right). They go on say that the distance value should be used. They don’t explain why most likely because it makes no logical sense. The latitude longitude estimate is mainly based on the distance calculations. The network triangulates the distance calculations to estimate the phone location. It’s the distance calculation that uses proprietary algorithms.

There is a subtle difference in the map of the distance value. In the 2017 figure there is a very wide line which isn’t explained but may be taken to mean there is some error factor associated with the distance value. The error value would be the width of the line in the 2017 figure. How they came up with the width of the line in the figure is unknown and most likely someone’s arbitrary decision how to draw the line. There is no value for the error factor of the distance to cell in the network operator’s historical call records.

You will notice that in the 2025 version the width of the line is very thin which indicates that there is no error factor to the distance estimate. This makes no sense either. The records do not have a column for distance error, but we know this is also an estimate. How do we know this? Because the only way to confirm the distance from the tower to a phone with 100% accuracy (or very close to it) is to take a measuring tape and measure it.

Any other method that doesn’t measure the distance will be an estimate and any engineer knows that if there is an estimate there MUST be a corresponding error or confidence factor. If there is no error factor, then one does not know the accuracy of the estimate and thus any depiction of it is misleading and goes against engineering principles and methods.

Hopefully, the SWGDE group realizes this and either modifies this inaccurate paragraph or just remove it altogether. I have testified in more than a few cases where the prosecution refers to this document and this paragraph in particular. It is wrong and unfair.