I went with a group of three or more, simply because of the vast number of people who have been questioned in this case. If George Mister is the villain that The Panolian reported him to be, and he describes Jessica as a close friend, I just get the feeling Jessica must have been caught up in something bigger than a simple lover's quarrel or a jealous female rival. The burning of the vehicle and the rumored pouring of accelerant in her mouth (may or may not be true) just seems incredibly vicious, and looks like a revenge or warning message, to me. If the accelerant in the mouth turns out to be true, I can't think of a stronger message that says This is what happens to people who talk.
Maybe I'm just too caught up in the seemingly infinite possible motives in this case, as well as the impression (as SteveP noted) that almost everybody in Courtland seems to have a felony charge lurking in the closet. With what Zool refers to as "the Alphabet boys" being involved, and the complete silence that has fallen over the community, I feel like this case may have a much larger scope than just one girl who made one other person angry.