When locations (almost) tell the story: Reconstructing road accidents from iPhone location-related traces

This study originates from a road traffic accident in which two vehicles collided in a curve. Alongside the physical evidence, location-related traces recovered from the Cache.sqlite database of an iPhone belonging to one of the drivers constituted the principal source of digital evidence. Beyond this specific case, analysis of these traces raised key forensic questions regarding their contribution to accident reconstruction. Based on these considerations, four investigative questions were defined, concerning the timing of the crash, phone manipulation before impact, speed estimation, and crash location. These questions were examined through a controlled experimental design involving 16 iPhone devices and high-precision Global Navigation Satellite System (GNSS) reference data, complemented by real casework observations. The results indicate that the moment of the crash can be approximated through speed analysis or spatial mapping of the recorded traces. Course values reflect the direction of motion rather than device orientation, thereby precluding their use for detecting phone handling. Speed values are reliable under steady-state conditions, but degrade substantially during braking. Regarding location, the analysis reveals three potential post-processing phenomena referred to as projection, correction, and anticipation. They can introduce significant positional errors, particularly around the moment of impact. These findings underline both the value and the limitations of iPhone location-related traces for forensic purposes. They further emphasise the need for a deeper understanding of their underlying creation mechanisms to ensure reliable interpretation in accident reconstruction.