Abstract: For audio forensic analysis, it is increasingly likely that multiple user-generated recordings (UGRs) may be presented as evidence in a criminal investigation. Audio evidence may come from handheld smartphones, private surveillance systems, police body cameras, and other unsynchronized recording devices. When multiple UGRs are available, the recordings could provide spatial and temporal information about the location and orientation of sound sources, and potentially a means to increase intelligibility of spoken utterances. However, UGRs generally start and stop at different times, differ in technical format specifications, and seldom have sufficiently reliable time stamp information for exact time and position synchronization. We study these analytical and practical constraints, and develop forensic recommendations for combining and synchronizing multiple UGRs.