Is it normal to assume one of your roommates stole from you?

I noticed that money had gone missing from me a week ago and I couldnt find it anywhere. I hadnt gone out b/c I was studying for my finals and I didnt spend it b/c I set it aside to pay for the utility. I looked through all of my belongings (purses, wallets, pockets, etc.), my clothes in the dryer, and I looked through the entire apartment, literally on my hands and knees, when everyone was out. I couldnt find it anywhere! I felt it was safe to assume it was stolen, but I simply went back to my parents house in an angry mood w/o saying anything b/c I didnt want to believe it.One of my roommates sensed something was wrong and txted me to what was wrongng and I told her how I felt. I already had suspicions towards one roommate but I just told her I thought it was unsettling that it was missing along with other things throughout the year. I suspected this particular girl b/c she is a pathological liar and I know she has stolen clothes and food from me before. Not to mention I have been around her when she has stolen and others have accused her of stealing before. The girl who I though did it txted me later about an angry fb status that had nothing to do with her and said she was sorry that I thought she stole it. I told her that the fb status wasn't about her and that it was stressing me out a lot and that I really hoped it showed up. The nxt morning I get a txt of a shady story of how the one who I thought stole it dropped her panties behind the washer and when she and another one of my roommates had to pull it out and that is when they found it still wet (after a week of sitting there). I had looked around that area and didn't see it and I have doubts with the story. I apologized for accusing them as a formality but they have been bitchy towards me and there is a lot of tension.
Is it normal that I believe the money was stolen from me and given back by a guilty conscious or am I just being paranoid?