He could have been a mass murderer, but his identity (and alleged crime) remains unproven still today. It's the story of an Illinois man who in the mid-1940s may have tried to gas his entire town.
This incident is a well-known tale about Mattoon, Illinois. It has its own Wikipedia page and was just retold by a prominent YouTube channel called Thoughty2. It's the story of the Mad Gasser of Mattoon.
The WIkipedia page for this alleged gas assault echoes what was described in the video:
The Mad Gasser of Mattoon (also known as the "Anesthetic Prowler," the "Phantom Anesthetist," or simply the "Mad Gasser") was the name given to the person or people believed to be responsible for a series of apparent gas attacks that occurred in Mattoon, Illinois, during the mid-1940s.
More than 2 dozen reports, but nothing was proven and no one was identified as the attacker. Police blamed the incident on mass hysteria created by women who were without their men who were overseas serving in the armed forces in World War 2.
It became a pop culture reference anytime a theory is brought forward about hysteria being created by public fear.
The University of Illinois states that 33 people claim to have smelt the gas over a 12 day period and some researchers now do believe it was possible if not likely there was a lone attacker.
But, is it possible that the attacker was an other-worldly being? American Hauntings believe it is. They theorize that a dimensional traveler could have staged the attacks and then reverted back to their own time.
Nearly 70 years later, the Mad Gasser of Mattoon remains a mysterious legend that fortunately did not result in the actual death of the victims.