Crimes landed him in jail for seven years between 1865 and 1874, most of which was at a reform prison in Oberstein Castle which contained 4,000 books.
He obtained a special right to borrow and read manuscripts and books. He read about foreign lands and studied maps.
His imagination grew wildly with visions of these exotic places.
This is where he started to develop his alter egos of Old Shatterhand and his Indian friend Winnetou.