Karel Keizer was a son of 524494.
Stadsarchief Amsterdam, archiefkaart Karel Keizer
Karel Keizer was a member of the 'Oranje Vrijbuiters', a team of heavies who were active in Utrecht, including for eliminating collaborators and for stealing coupons. on 29 August 1943, the Nazis wound up the team.
In February 1944, 20 team members were put on trial, 19 of which were given the death sentence. They were executed on 29 February 1944 on the Waalsdorpervlakte. The 33 year old Karel Keizer was among them.
NIOD, Erelijst Verzet en Koopvaardij, database made by J.W. de Leeuw;
B. Braber, Zelfs als wij zullen verliezen. Joden in verzet en illegaliteit in Nederland 1940-1945 (Amsterdam, 1990) 130
E.P. Weber, Gedenkboek van het Oranje Hotel