A while back I had a coworker who was just strange. I took a personal day one day, and came back to find my monitor (that I had brought from home) was gone. I was asking the people who worked around me where it went and after no one knew, I found it on someone else's desk. When I explained to him how I had brought it from home he denied he took it from my desk and continued that it was HIS from home! Turns out he had been taking other people's equipment around the office as well. He would rearrange furniture and even take down other people's personal decorations. He was eventually let go...