Cell Tower Records and Tarot Cards

You got a methodology in there somewhere?

Photo by Viva Luna Studios on Unsplash

I have been fortunate enough to be an expert witness in a few cases involving cell tower evidence, where the prosecution attempts to place a defendant at a crime scene based on records from their mobile operator. Most start out the same way:

1. The defense attorneys send me a law enforcement evidence report with some maps purporting to show cellphone activity.
2. I make my initial review of the report and tell them, “It doesn’t really say anything about where the phones were.”
3. They say, “That’s what we thought, too, but since we aren’t experts, we couldn’t be sure.”

In my first article on cell tower evidence, I gave some commentary about the weakness of the “nearest-cell” methodology typically used by law enforcement. What I usually find in practice, though, is no methodology at all, just a map presenting the raw records, with no analysis and no conclusions. The preface to the report may define a nearest-cell kind of methodology, apparently unused, and if the defense challenges the law enforcement expert on the accuracy of the report, he/she will probably give a figure north of 95%. None of it adds up to anything that makes sense.