Techniques are described for tracking intruders of a monitored property by the unique identifying characteristics or “digital fingerprints” of electronic devices carried by the intruders. A system detects an alarm event at a monitored property based on output from at least one sensor located at the monitored property. In response to detecting the alarm event at the monitored property, the system initiates a process to gather electronic identifiers for mobile electronic devices located within the monitored property at a time corresponding to the detected alarm event. The system determines electronic identifiers for the mobile electronic devices located within the monitored property at a time corresponding to the detected alarm event. The system stores in electronic storage, information indicating the determined electronic identifiers for the mobile electronic devices located within the monitored property at a time corresponding to the detected alarm event.