<human>: Hi Reddit! I've been a lurker for quite some time now, but I've finally made an account to post about a problem that I'm hoping some of you might have ideas how to solve. Read on at your own risk -- it's pretty gross.

I'm a Resident Advisor in one of the residence halls at my university, and we've recently been having a problem with a bathroom on one of the floors. Some mystery resident (aka the Phantom Pooper) keeps using the restroom, and when finished, the Phantom Pooper decides to smear their poop on the toilet seat and the walls around the toilet. They even draw pictures with it, I kid you not. The worst part? This has happened **20 DIFFERENT TIMES**. And yet, this person has somehow managed to never have been caught in the act.  It's absolutely disgusting.

The doors of the restroom are locked 24/7 except to those who live on the floor, so unless somebody is giving their key away to another person, the culprit has to be somebody who lives on that floor. The phantom pooping has occurred at varying times of day -- sometimes late at night, and other times right smack-dab in the middle of the afternoon. Everybody is beginning to point fingers at who they personally think the culprits are, and the floor is slowly turning to chaos. Obviously we can't put video cameras in the bathrooms, and unfortunately, we aren't allowed to restrict access to the bathrooms in any way. We're fresh out of ideas on how to solve this issue, and it's becoming frustrating.

So I pose a question to you, Reddit: How can we catch/stop the phantom pooper? Any ideas?

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Someone keeps smearing poop on the walls in our dorm. How can we catch him/her and stop this madness?