He wants to know a lot! Luckily Ema is nothing short of ecstatic to explain.

"Well, obviously, the goal is to learn all you can about a crime, so you know who committed it. The techniques I've used are finding fingerprints, and finding blood splatters. I use luminol for the blood splatters, you spray it from a bottle..."

She'll babble on about it for awhile as they walk, until they get to the cafeteria. "...of course, fingerprints are useless if you don't have a match on file, and... oh, is this it?"