Joe was eventually rescued from a sewer system after a passerby in the area heard noises from a manhole cover early Saturday morning and alerted emergency services, the Oldenburg-Stadt / Ammerland police said in a statement on 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 did not believe anyone else was involved in the incident.
An initial police report described Joe as having a learning disability. As the investigation continued, they said he could misinterpret it as a game and continue to hide.
Joe’s last name has not been made public, according to German privacy laws.
Immediately after the rescue, investigators began scanning the sewer system for clues as to how it disappeared.
Authorities concluded that Joe probably climbed into a concrete sewer pipe while playing and then crawled into the sewer system through a canal and disappeared after several meters.
The researchers said that between the entrance to the sewer system and the spot where Joe was found, there were drainage wells and intersections at regular intervals where he could stand.
Joe told police in an initial statement that he was becoming increasingly disoriented while stuck in the sewers and could not find his way.
“We are so happy – really,” police spokesman Stefan Klate told CNN’s N-TV subsidiary.
“This is absolute luck. Of course, there was a chance we would not have found the child there. Possibly – if he had not made a sound or these noises would not have been heard, then we might not have found him there at all,” Klatte added.
