As I was reading your story I thought it was just a guy who hung out around your office dumpsters picking through them...not another employee!
When he was hired he was fine. He had a terrible auto accident and was slightly brain damaged from it. The company found menial jobs for him to do and he did OK for several years, but as he got older he got worse. I don’t know for sure but I don’t think they actually “fired” him. That is what they called it but I think they helped him get some kind of disability for mental disabilities. The rumor was that they did.
He was sort of pitiful. He scrounged in all the trash cans and saved everything. He saved used tape, pieces of string, paper clips, even splinters of wood from pallets. He checked all the vending machines in the cafeteria to see if anybody left their change and felt around under the cushions in the lounge. He was well paid and there was no reason other than mental problems that would cause this kind of behavior. He worked on the manufacturing floor and he was never on his actual job. He was always prowling in trash.
He eventually got so bad that he was a liability to keep around the workplace. I’m sure they took care of him though. They have done it for other people.