according to that article, the train and station already had surveillance cameras. the current post and comment thread are about surveillance microphones; how w

according to that article, the train and station already had surveillance cameras. the current post and comment thread are about surveillance microphones; how would that help with the investigation in your article, where we can reasonably assume that the robbers were shouting things like "open your bag" and "give me your wallet", and interview witnesses to confirm our assumption?