Jacques was adopted in September 1925 by Isaac Mok and Judith Erwteman, living with them in Tolstraat 39hs since 1929. After Judith's death in September 1931, Isaac remarried Rebecca van Collem in February 1932. Jacques attended the Lutmaschool and worked as a diamond cutter. He frequented Heck’s lunchroom on Rembrandtplein with his friend Wolf Tokkie. Jacques was unaware of his half-sister Adriana Janine until the end of the war.
On July 14, 1942, Jacques visited his fiancée Frieda Wolder, despite warnings of roundups. He was likely arrested near Cornelis Troostplein or Apollolaan. Jacques was among those held as hostages and later transferred to Westerbork on July 25. On July 27, he was transported to Auschwitz, where he died on August 23, 1942, from typhus. His parents went into hiding after he didn't return, living with the narrator's grandparents in Amersfoort until liberation, unaware of Jacques' fate. Jacques was 21 years old at the time of his death.
