I live in a house with five college students, and I often find my stuff missing from my room. Whenever I ask if anyone has seen my items, no one knows where they are. However, two days later the item reappears. I have a lock on my door so no one should be in there. I was starting to think I was going crazy. I finally ended up installing hidden cameras to see if it was just me or if someone was entering my room when I was at work. After about a week I was able to watch the tape. I realized that one of my roommates would come and go from my room regularly. He either picked the lock or had a duplicate key.