See below how this drama depicts the imager as "seeing" a sharp outline of a living human body inside a metal office supply cabinet. Any volunteers to recreate this scene and show how this would really appear?
In real life, they'd just send in a police dog.
I doubt real-world crime scene investigators have this particular piece of technology available, but giving investigators expensive or outright non-existent tools is par for the course for television in general, and the CSI franchise in particular. Overstating the capabilities of thermography is a common TV Trope, often attributing to these cameras visualization not even feasible with millimeter wave radar.
