Take a closer look.

Taking the magnifying glass out of your inventory, you take a closer look at the one clean spot on the monitor. Seems like the path of a finger. Slim, clean, deliberate. You check both ends of the line, and bingo. You can see the faintest fingerprint in the dust. If the cops were still around, you could ask them to see what they can do about identifying the print. Seems you'll have to get creative.