Mendel was raised in a large, Yiddish-speaking, religious Jewish family in Sokolow Podlaski, a manufacturing town in central Poland with a large Jewish population of about 5,000. Upon completing school, Mendel worked as a shoemaker. He was also active in a local Zionist organization.
1933-39: Mendel was married and had a family when the Germans invaded Poland on September 1, 1939. Aircraft bombed the town's market and other civilian targets before victorious German troops marched into Sokolow Podlaski on September 20 and began to loot homes in the Jewish community. When Poland was partitioned between Germany and the Soviet Union, Mendel and his family fled to Bialystok in the Soviet-occupied part of Poland.
1940-44: Like other Jewish refugees from Poland, Mendel feared the Nazis' treatment of Jews and hoped to save his family by staying in the Soviet Union. But Germany attacked the Soviet Union on June 22, 1941. Five days later, the Germans had reached Bialystok. On July 16, 1941, the Nazis established a ghetto in the city, and most of the people in the ghetto were put to work in industries. In August 1943 the Nazis liquidated the Bialystok ghetto.
Mendel was last seen by friends in Bialystok. He perished some time after June 1941, but no one knows where, when or how he died.