Reddit mentions of The Mad Gasser of Mattoon: Dispelling the Hysteria

FWIW, I have a book which covers this case (among others) ; the authors think the gasser was a young man (a brilliant chemistry student, homosexual, and emotionally disturbed) who was targeting his ex class mates for socially isolating and bullying him, because of his sexuality mostly. The authors also claim the family had him put away (apparently for the rest of his life) in a mental institution, and the last few attacks were committed by his sisters, so no one would connect his sudden absence with the attacks ceasing. FWIW...If anyone wants to read the book and decide for him/herself, it's Myths and Mysteries of Illinois, by Richard Moreno. It makes for an interesting theory or story, anyway.

ETA : Just reread the MG part of the Moreno book ; he is actually quoting Scott Maruna's version of events, as laid out in The Mad Gasser of Mattoon: Dispelling the Hysteria. As I decline to pay several hundred dollars for a used paperback published as recently as 2003, I will trust that Moreno described Maruna's theory accurately.

I read this book about the case way back when. The author, Scott Maruna, an Illinois native, did a ton of research on this story and presents a very educated, informed and logical case for the identify of the Gasser. Not everyone will agree, naturally, but the circumstantial evidence he presented was quite strong.