 By other accounts, he met with family members just across the German border, and on a later date a TV crew took footage of him standing over the border itself, one foot daringly extended on to Dutch soil.Throughout the years Princen maintained correspondence with his younger brother Kees, as well as with his mother, who in the 1940s had tried to intercede for him with the Dutch military authorities – a correspondence eventually deposited, together with many of his other papers, at the Amsterdam-based International Institute of Social History (IISH).As mentioned, he was a valued reporter for various Dutch communications media.