Egon Spengler a room for hours and gradually raising the temperature. A positive test involved a girl in a room with dozens of stuffed animals and a puppy. He was the first person Dana Barrett contacted when her baby carriage took off by itself. Egon recommended bringing in Ray, and they both performed a physical exam on Dana's son Oscar. Egon, along with Peter and Ray were later arrested after digging a large hole under First Avenue as part of their paranormal investigations to help Dana. During the course of their trial they were found guilty of willful destruction of public property,
Egon Spengler intellect switched with Slimer's. He has however, ceased his sugar junkie ways, only to briefly be tempted by a candy store when in Slimer's body (a likely fact that Slimer was an overt glutton). It is revealed in "The Boogieman Cometh" that, as a child, Spengler was stalked by the boogieman, a supernatural monster that fed on the fear of children and hid in their closets, and was particularly fond of Spengler's fear; it was these encounters with the creature that inspired Spengler to study the paranormal, and as an adult, he would battle the Boogieman twice and defeat him.