if you think the Best Buy is too public a place to commit a murder, you should see the library after school, swarming with kids.
Here I think that Koenig is appealing to logos. She explains that if the murder didn’t happen at best buy, then couldn't have happened at the school library. She explains this is because the library is always swarming with kids; the audience can easily understand this. Ultimately the way Koenig explains it makes sense in a more logical way giving her more support on her other observations and that ups her credibility to the audience.