Born in
Berkhout, a small town in
West Friesland, Jonker moved to Amsterdam at the age of 13. During
World War II, he had a job at the Amsterdam office for
resident registration and got involved with the
Dutch resistance. Photographer Marie Östreicher (better known as
Maria Austria; the
Maria Austria Institute in Amsterdam is named for her) taught him the techniques of photography, and he was able to forge personal identification documents for the resistance, until he had to go into hiding in 1944. Tall and blond, on occasion he dyed his hair black and, disguised as a female nurse, took photographs of Amsterdam documenting the German occupation. These photographs were used as documentary evidence of the occupation, and to strengthen morale and raise funds for resistance activities. During this period he used the aliases Gerrit Boersma, Frans Kreder, and Hélène Annie Smitshuisen. Jonker arrived in Zeeland with the very first aid workers, and photographed people standing on the roofs of their homes. His work appeared in
Der Spiegel and
Time, and nationally in
Margriet and
Algemeen Handelsblad. ==Legacy==