True story: when I was in college and living in a cottage with another woman (who at that point was spending all her time at her boyfriend's), I came home late one night, walked through the front room into my bedroom and it was completely torn apart. Every piece of clothing on the floor, dresser drawers pulled out and dumped, etc. I didn't feel alarm or call the police. Instead, I called my roommate and asked if she'd been looking for something in my room. Sounds unbelievable, but that's what I did.
She immediately said, "It's a break in! Get out of the house, we'll be right there!" Sure enough, a burglar had climbed through her bedroom window (I never noticed the draft from the open window even though it was winter), stolen the jewelry from the top of her dresser (but touched nothing else in her room) and thrown everything around my room (but nothing of mine was missing).
It could easily appear that I "staged" the disorder in my room to cover the stolen jewelry from her room. I even had a brand new in the box car stereo in the front room that wasn't taken.
Fortunately, the burglar also took a 6-pack of beer out of the refrigerator, drank one, and left fingerprints that way that led to his arrest.
Why wasn't I more alarmed? Why didn't I call the police right away? Why was my room tossed and hers not? Why wasn't anything of mine taken? That's just the way it happened.