Isn't she unpleasant? It's obvious, after a little conversation, that she's not going to cooperate with you without a little pressure. We need more info here. Who else is there who might know something about her that we could use?
The only person is Adrian, the RA, so go talk to Adrian and ask him everything.
Kelly told you that JoAnn slept all night. However, Adrian tells you that Kelly doesn't sleep in the dorm most nights. That disconnect is significant, but Rosa needs a little help to draw the obvious conclusion here. That means it's notebook time.
Click on your notebook (in the upper left corner of the menu) and click on "JoAnn slept all night," then on "Kelly sleeps elsewhere." This gives you a new notebook item.
Now go back to Kelly and click on "Did Kelly lie?" After this, she'll be slightly more cooperative, so ask her everything again until she repeats herself.