My daughter is his age and reads on a 5th grade level also, so I asked her for recommendations. Her first choice is the Cam Jansen books. They are not scary or gory, and are age appropriate. These were a quick read for her (around 3rd grade reading level) , but she says she thinks your son will like them.
She also read the Bailey School Kids series, but they may be a little too much for him if he is very sensitive. She won't admit it, but I think there were some of these that were too scary for her to finish. The premise in each book is that various teachers at the school may be monsters, and there really is no resolution either way at the end.
She also read the Bailey School Kids series, but they may be a little too much for him if he is very sensitive. She won't admit it, but I think there were some of these that were too scary for her to finish. The premise in each book is that various teachers at the school may be monsters, and there really is no resolution either way at the end.