The gasser's supposed victims reported smelling strange odors in their homes which were soon followed by symptoms such as paralysis of the legs, coughing, nausea and vomiting.
Most contemporary descriptions of the Mad Gasser are based on the testimony of Mr. and Mrs. Bert Kearney of 1408 Marshall Avenue, the victims of the first Mattoon case to be reported by the media.
Suspecting that he was suffering from domestic gas poisoning, Raef's wife tried to check the kitchen stove to see if there was a problem with the pilot light, but found that she was partially paralyzed and unable to leave her bed.
[5][3][7][8] Later that night (some contemporary accounts refer to the time as the morning of the following day), a similar incident was also reported by a young mother living close by.
The first specimen of physical evidence was found on the night of September 5, when Carl and Beulah Cordes of North 21st Street returned home around 10:00 pm.
After spending a few minutes in the house they noticed a piece of white cloth, slightly larger than a man's handkerchief, sitting on their porch next to the screen door.
Beulah Cordes later hypothesized that the cloth had been left on the porch in order to knock out the family dog, which usually slept there, so that the prowler could gain access to the house unnoticed.
[10] In addition to the cloth, a skeleton key, described as looking "well used," was reportedly found on the sidewalk adjacent to the porch, along with a large, almost empty, tube of lipstick.
[7][8] By September 12, local police had received so many false alarms (mostly from citizens believing that they smelled gas, or that they had seen a prowler) that they reduced the priority afforded to gasser reports and announced that the entire incident was likely the result of explainable occurrences exacerbated by public fears, and a sign of the anxiety felt by women while local men were on war service.
[5] (List incomplete) [5][3][4][7][8][13][14] There are three primary theories about the Mattoon Mad Gasser incident: mass hysteria, industrial pollution, or an actual physical assailant.
Almost two weeks after the Mattoon attacks began, the local Commissioner of Public Health, Thomas V. Wright, announced that there had undoubtedly been a number of gassing incidents, but that many instances were likely due to hysteria: residents hearing of alarming events, and then panicking when confronted by an out-of-place odor or a shadow at the window; Wright stated:[7] There is no doubt that a gas maniac exists and has made a number of attacks.
The whole town is sick with hysteria.On September 12, local Chief of Police C. E. Cole took Wright's hypothesis a step further, announcing that there had likely been no gas attacks at all, and that the reported incidents had probably been triggered by chemicals carried on the wind from nearby industrial facilities and then exacerbated by public panic.
On September 12, Chief of Police Cole told a press conference that odors and symptoms reported may have been the result of pollutants or toxic waste released by nearby industrial plants, and speculated that carbon tetrachloride or trichloroethylene, both of which have a sweet odor and can induce symptoms similar to those reported by purported gasser victims, may have been the substance released.
[12] After analyzing events, some researchers have concluded that at least some of the gasser incidents were the work of an actual attacker who carried out a series of gassings as reported by witnesses.