Joe was eventually rescued from the sewer system after a passer-by in the local area heard noises coming from a manhole cover early on Saturday morning and alerted the 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 was taken to a nearby hospital, where he was treated for hypothermia and dehydration.
Police said they didn’t believe anyone else was involved in the incident.
An initial police report described Joe as having a learning disability. While the search was ongoing, they said he might misinterpret it as a game and continue hiding.
Joe’s surname hasn’t been made public, in accordance with Germany’s privacy laws.
Immediately after the rescue, investigators started scanning the drainage system for clues to how he disappeared.
The authorities concluded Joe most likely climbed into a concrete drainage pipe while playing, and then crawled into the sewer system through a canal and got lost after several meters.
Investigators said that, between the entrance to the drainage system and the place where Joe was found, there are drainage manhole shafts and junctions at regular intervals where he was able to stand up.
Joe told police in an initial statement that he became increasingly disoriented while stuck in the sewers and was unable to find his way out.
“We are so happy — truly,” said police spokesman Stephan Klatte, according to CNN affiliate N-TV.
“That is absolute luck. Of course, there was a possibility that we wouldn’t find the child there. Possibly — if he had not made a sound or these noises would not have been heard, then we may not have found him there at all,” Klatte added.