László Weiss was born in Budapest to Joseph Weiss and Ilona Ujhelyi. He studied painting at the Budapest art academy and travelled Europe after graduating. He married in London in 1929 and then settled in the Netherlands with his wife. They had three children.
László Weiss became a partner in the advertising agency R.A.B.A.G. on Zwanenburgwal in Amsterdam. Later he started his own agency, 'Roland & Co' (Roland was his professional name).
During the war, László Weiss was left undisturbed for a long time. He claimed to be Catholic. It has not been established whether he was Jewish. The Weiss family hosted a Jewish woman who was in hiding. In June 1944 László and the Jewish woman were arrested and taken to the Gestapo office on Euterpestraat. László Weiss was sent to Camp Vught. From there he was deported to Sachsenhausen and then to Bergen-Belsen, where he died of epidemic fever.
Addition of a visitor of the website
For additional information see the biografie van László Weiss. Also there is a new project on Geni.com about the loose ends in the story of László Weiss; László Weiss - The loose ends.