I spy with my little eye

[Frank_Stein]

Also, I think that the detective should have some manner of non-bullet bug he can discreetly plant onto people a la sleepy pens, or maybe give him a special radio that can be placed in his hat or in pockets or what have you with a similar function. As an AI who makes frequent use of the station intercoms at every opportunity, being able to pick up on what doesn't get put on the radio is a very valuable tool.

I love the way the gold star stickers work, and a more subtle sprite for a bug that that can be applied the same way would be nice.

There should be a way to detect them, though. Maybe some kind of assembly using a radio that beeps the closer it gets to one?