MOTHERBOARD: Hey, Professor Imwinkelried. The reason I’m calling you is because I saw your name cited as a source in a Washington Post article written by Tom Jackman this year, and in turn that article was referenced in Serial. Have you heard of Serial? The podcast?
​Imwinkelried: No, I’m afraid I haven’t. No.
MOTHERBOARD: Oh OK, never mind, I’ll just jump into it: Is the use of evidence gathered from cell-phone towers reliable and accurate when trying to pinpoint a person’s location, say, in a murder case?
​​Imwinkelried: The important thing to realize is that cell-phone technology was not designed as a technology for locating people. It’s a communications technology. It’s one thing when using a technology specifically designed for locating—GPS—it’s another thing when you try to adapt a technology which was never designed for that purpose.
GPS is the technology to locate people. The problem is, in the past, many of the cases have involved cell phones without GPS, and there they’ve been relying on these supposed assumptions that the phone connects to the closest tower, or the tower with the strongest signal.
MOTHERBOARD: So they’re not reliable at all? Location evidence gathered using cell-phone towers isn’t good science?
​​Imwinkelried: They were never intended to serve that function.
The decision as to which tower to connect to isn’t made by the cell tower, it isn’t made by the phone, it’s made by the network computers. And what are the network computers interested in? Balancing the load, using all the towers in the network.
And that’s why you can sit in your room in a 10-minute period, make three cell-phone calls, and connect to three different towers. You haven’t moved at all, but you’ve connected to three different towers.
