Today I came into work and sat down in my cube and habitually immediately reached for my coffee cup. I know I cleaned it last night because I always do. I thought I've noticed before that my cup has a residue in it that wasn't there when I left, but this time I know fo a fact some &^@hole has been using my cup at night. I suspect the night cleaning crew. We're a small company and don't hav e a formal security group to report this to. I hate to have to say anything to the cleaning company in case it isn't one of their people.

Any ideas as to how to determine with certainty who's doing this? Assume that DNA testing and hidden video cameras are out of the question.
Your inputs would be appreciated. This could be fun while netting a scumbag.

Loren - Cinci, OH

Simple solution.

Swab a few drops of striccnine around the rim of the cup tonight. Look for the body in the morning. Works every time!!!

Oh, don't forget to wash the cup before you use it. Come to think of it, you might just want to throw it away.

Any more problems you need a solution to?

Leave a dead cockroach or a spider or something in your cup when you leave work.

If it is still there in the morning, you know the culprit learned his lesson. If it is not there in the morning.... well... at least you got even !

Here is something slightly noisier.

Get one of those musical greeting cards and take it apart. Tape the music generator to the bottom of your cup and rig it with thread so it starts playing if the cup is moved.

Not as much fun as a roach or a spider, however it does involve electronics, and it will make a "gotcha" noise.