He died during World War II, after being arrested in France and sent to the Nazi German Auschwitz concentration camp c. 1943–1944.

[1][2] Słodki was born to a secular, liberal Jewish family in Łódź (then part of the Russian Empire).

From 1910 to 1913 Słodki studied in Munich at the Academy of Fine Arts and then spent the next year travelling through Europe.

[2] Following the German invasion and occupation of France, he lived in Brive-la-Gaillarde, first continuing with his public work, even exhibiting it, but eventually going into hiding.

After the Germans took control of Chambéry, he was arrested again, on 14 December 1943, and was sent to the Auschwitz concentration camp where he died within a year.