This case involves a rape suspect who was tracked by his cell phone. The defendant was taken into custody and the DA obtained evidence using cellular technology against him from cell towers, which are believed to have tracked his whereabouts through his cell phone around the time of the rape. A number of experts were retained for this matter with specializations in telecommunications, audio forensics and voice identification.
Question(s) For Expert Witness
- 1. How accurate is tracking data obtained by way of a cell tower (especially in densely populated areas)?
Expert Witness Response E-004629
In this situation, there would be a difference in phones that have GPS and those that do not have GPS. If the phone has GPS, and it is enabled, the location of the defendant can be tracked fairly accurately. However, if there is no GPS, then it would be very difficult to track a position. For example, normally a phone would be using the closest available cell phone tower. The case is different, however, in densely populated areas. Cell phone towers are often very busy in these areas, so a cell phone’s signal could jump from tower to tower. In addition, the presence of buildings may interfere with the signal. Of course, the records will reveal if the data corroborates the plaintiff’s claims. I am a professional electrical engineer who has worked on software systems for over thirty years. I currently work as a forensic engineering consultant and I am certified in data processing. I am especially qualified on issues of cell phone tracking because I previously testified about using cell phone data to locate a person in other criminal prosecution cases.
Expert Witness Response E-004633
Much depends on the carrier and technology involved to determine what data they collect and how definitive it is. At best, one can infer rough location (along a radius) and estimate an approximate speed (minimum-maximum). Many things can throw this off including tower placement, obstructions, and diffraction of signal. I have twenty-three years of experience in the telecom field. I perform a wide range of consulting duties for wired and wireless telecommunications, with a concentration in call center technology. Recent projects include an analysis of wireless carriers (coverage/reliability/cost), and a campus wireless handset project within a hospital network.