I wouldn't use the poison bait - they will die and the odor will be nasty for up to a month depending on where they die.

Theodore - I don't recognize the color, but I would send the photo to a couple of "big box" stores and see what they suggest.

@Sam Booth Yes to the Oil based Kilz on the sub flooring or something similar to help kill the odor.

On entering the bathroom, I discovered the powder, and the odor, were INCHES of talcum powder on the floor where this person apparently "bathed" with the talcum powder, then carried/spread it throughout the apartment.

If you're in the area, ask the tenant to contact you when they smell the odor, then drive over and confirm.

Quote from @Theodore Turner: Quote from @James Krahula: I have Pace Morby's contract that has all of those protections and then some, I'll send that your way. 

Was a primer used over the area that the odor is originating from?

If the odor is not properly mitigated that will cause ongoing problems.

So take the time to first use the odor removers, and let those dry.

I will say the odor was pretty strong too.