Jim Kendall is not a man who is loved by people in that small town, although some people find his jokes funny as long as they are not on them. There are many examples of those on whom Jim always makes annoying jokes such as Milt who "has got an Adams apple that looks more like a mushmelon" Julie Gregg and especially Paul Dickson who fell out of a tree when he was about ten years old : "Lit on his head and it done something to him and he ain't never been right. No harm in him, but just silly." Paul is the most important one among them because of two reasons: He is not as clever and reasonable as the others and he is the one who was killed Jim Kendall. Of course these do not prove that the killing of Jim is on purpose. However there are some more reasons that can cause Paul kill Jim on purpose.
As we understood from what is told, Paul is fall in love with Julie although she just feels pity on him : "The poor boy was crazy about Julie and she always treated him mighty nice and made him feel like he was welcome, though of course it wasn't nothing but pity on her side" But according to Paul, Jim never treated her right. He faked her by mimicking Doc. Stair when Doc. Stair was away and made her come to doctor's office. By the way he and some of his friends hid near the office and laugh at her when she realized the trick. They made fun of her till she got home. Later, when Paul learned this he told the whole story to Doc. Stair. He replied Paul that he would make Jim suffer some how : "It's a chinch Doc went up in the air and swore he'd make Jim suffer"
These words from Doc. Stair may well encourage such a person like Paul about punishing Jim Kendall in his own way.
We do not know exactly how old Paul is but it can be assumed that he is not very old, he may be...