Joe was eventually rescued from the sewer system after a passer-by in the area heard a noise coming from a manhole cover early Saturday morning and alerted emergency services, the Oldenburg-Stadt/Ammerland police department said in a statement Tuesday.
Joe was found just 1,000 feet from his home address and taken to a nearby hospital where he was treated for hypothermia and dehydration.
Police said they do not believe anyone else was involved in the incident.
In the initial police report, Joe was described as being unable to learn. While the search was going on, they said that he could take it for a game and continue to hide.
Joe’s last name is not being released due to German privacy laws.
Immediately after the rescue, investigators began scanning the drainage system for clues as to how he disappeared.
Authorities concluded that Joe most likely climbed into a concrete drainage pipe during the game and then crawled into the sewer system through a channel and got lost after several meters.
Investigators said there were drainage wells and connections at regular intervals between the entrance to the drainage system and where Joe was found where he could stand up.
Joe told police in an initial statement that he became increasingly disoriented while stuck in the sewers and could not find his way out.
“We are so happy – really,” police spokesman Stefan Klatte said, according to CNN affiliate N-TV.
“This is absolute luck. Of course, there was a possibility that we would not have found the child there. Perhaps – if he had not made a sound or these noises had not been heard, then we might not have found him there at all. “Klatte added .