He first turned up nine months ago and is reported to have lived in the forest for a time.
German police distributed a photo of the young man on Wednesday in the hope of identifying him. He was recognised by friends in the Dutch town of Hengelo.
He had been experiencing personal problems and had disappeared in September of last year.
The German police carried out a DNA test to see if the young man was Liam Vanden Branden who disappeared from the garden of his home in Mechelen on 3 May 1996. However, the test was negative.