Establishing phone-pair co-usage by comparing mobility patterns

TL;DR

This paper introduces a transparent logistic regression-based method using cell tower data to determine if two phones were used by the same individual, validated on real-world data for forensic applications.

Contribution

It presents a novel, validated approach combining logistic regression and kernel density estimation for forensic phone co-usage analysis.

Findings

Good performance across different models

Robust under limited data quality

Applicable in forensic court cases

Abstract

In forensic investigations it is often of value to establish whether two phones were used by the same person during a given time period. We present a method that uses time and location of cell tower registrations of mobile phones to assess the strength of evidence that any pair of phones were used by the same person. The method is transparent as it uses logistic regression to discriminate between the hypotheses of same and different user, and a standard kernel density estimation to quantify the weight of evidence in terms of a likelihood ratio. We further add to previous theoretical work by training and validating our method on real world data, paving the way for application in practice. The method shows good performance under different modeling choices and robustness under lower quantity or quality of data. We discuss practical usage in court.