The laser Doppler vibrometer (LDV) is a promising tool for lawful police surveillance. This instrument can detect minute vibrations (~5 nanometers) in objects from as far away as 300 meters. In particular, the laser can pick up vibrations in materials produced by human speech and activity. The patterns formed by such vibrations, with the aid of signal processing and machine learning software, can be used to reproduce faithfully the original speech and activity in real time. For example, if a criminal suspect is having a conversation with a confederate in a restaurant and there is no opportunity of planting a listening device beforehand, a laser, beaming signals through a window at a wall or object near the speakers, could be used to “record” the conversations. State-of-the-art artificial intelligence techniques such as statistical signal processing, machine learning, and deep computing algorithms can be harnessed reliably to reconstruct conversation and sense other human activity, thus helping police in their fight against crime and terrorism.