We consider the problem of identifying insider-based attacks in the form of jammers in multi-channel wireless networks, where jammers have the inside knowledge of frequency hopping patterns and any protocols used in the wireless network. We propose a novel technique, called "alibi", to identify the insider-based jammers in multi-channel wireless networks. Alibi is a form of defense whereby a defendant attempts to prove that he or she was elsewhere when the crime in question was committed. Starting from such simple concept, we develop an alibi framework to cope with insider-based jamming attackers in various situations including single/multiple jammer and lossy channels. We evaluate the framework according to several properties such as accuracy, detection time and network performance via TOSSIM simulation and analysis. The overall results of these protocols show a promising research direction to deal with insider-based jamming attacks.