Casper mentions, during the scene in the attic, that as a young boy he wanted a wooden sled around winter time. He begged his father to buy him the sled; however, his father was concerned, as Casper didn't know how to ride it. Then, one morning when Casper came down for breakfast, he found the sled in the kitchen. An ecstatic Casper then took the sled outside. After many hours of sledding, Casper was ordered by his father to come inside, as it was getting late and the temperature was getting colder, but Casper, having too much fun, ignored him. By nightfall, Casper contracted pneumonia.
McFadden obtained medical help for Casper, but it was it was to be in vain, for his son's condition was too severe to cure. Casper then passed away, leaving his father devestated. Not wanting him to be alone, Casper refused to cross over into the afterlife and returned to his father as a ghost. McFadden would become frightened by his dead son as a ghost. Through several newspapers, he told his story about how he was haunted by the ghost of his dead son, but none of his statements were believed. McFadden would later decide to use his scientific genius to invent a machine that could turn ghosts back into humans. He called the invention the Lazarus, which is named after the man in the New Testament who was raised by Jesus from the dead. McFadden was soon arrested by local authorities after nearly completing his machine and was sent to an insane asylum.
It was unknown when McFadden died, but he is mentioned by Amelia Harvey. Amelia told Casper that his father won't forget how he used the machine to bring back Kat's father Dr James Harvey from the dead and that he fullfied his greatest dream, which was to give the dead another chance at life beside their loved ones. She also makes it clear that his father is very proud of him. Casper would later get his dream in return by becoming human himself, but it was only for that one Halloween night.
- The Ghostly Trio mention Casper's father in one of the film's deleted scenes.
- An old newspaper article that has a picture of McFadden is picked up and read by Kat during the attic scene. This was probably one of the newspapers that McFadden told his story to the media about Casper.