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HaLo is a hand-held device transferred from Nokia n900 smartphone for real-time localization of a suspect who is conducting crimes in a wireless crime scene. We collect only wireless signal strength information, which requires low level legal authorization. For private investigations on campus, it does not require only legal authorization. The idea of localization is to collect wireless signal strength samples while walking. The position where the maximum signal strength is measured will be a good estimate of the suspect device’s location. 


The key challenge of accurate localization via the hand-held device is that the investigator has to control its walking speed and collects enough wireless signal strength samples. We found that the digital accelerator on a smartphone and GPS are very often rough for measuring walking speed. We propose the space sampling theory for effective target signal strength sampling. We validated the localization accuracy via extensive experiments.


Junwei Huang, Yinjie Chen, Zhen Ling, Kyungseok Choo, Xinwen Fu, A Framework of Network Forensics and its Application of Locating Suspects in Wireless Crime Scene Investigation, in Proceedings of the 7th International Workshop on Systematic Approaches to Digital Forensic Engineering (SADFE'12), Vancouver, Canada, September 28, 2012.