Karel Simmelink was a primary school teacher [1#1] at the Paredis School in Roermond. 
Joseph Johannes Wilhelmus Simmelink, Karel’s father, was headmaster of the same school  and also active in the resistance. In the Carpe Diem, the summer house of Simmelink sr. in the woody Leu valley near Nunhem, the Oranje Post was produced. (Cammaert XI p.1074 )
Karel went into hiding when he as a demobilized soldier had to go into captivity of war again. Member of the Resistance (LO-Roermond and Ordedienst) under the pseudonym Jan van der Plas. 
We also read about Karel on Traces of War:
After a meeting at his parents’ house – ‘het Kasteeltje’ – in Nunhem on June 28, 1944, he was arrested early the next morning together with his father and the vicar Emile Goossens  from Echt, who had been hiding with the family for several weeks. The SiPo  had indications that Ensign A.J. van Rooyen, who was suspected of clandestine activities, was also in hiding with the Simmelinks. During the raid, Van Rooyen managed to escape. Dad Simmelink was freed from the Maastricht prison on the day his son was shot along with about 60 fellow prisoners. 
Karel Simmelink had been transferred from Maastricht to Vught  a few days before. There, on September 5, 1944, he was murdered in the firing range used as an execution site, as part of mass shootings because of the approach of Allied troops (Deppner Executions ).
He is commemorated in the following places: