Establishing phone-pair co-usage by comparing mobility patterns.

• Cell phone users can be identified by comparing mobility patterns from usage data. • Call Detail Records, widely used for intelligence, are also forensic evidence. • Our results can be used in court when precautions are taken into account. • Data quality has more impact on performance than sophisticated models and features. 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. [ABSTRACT FROM AUTHOR]