[1][2] Their father Isucher Moshe Szwarc (1859–1939) was an Orthodox Jew heavily involved in Zgierz's Jewish community and the late Haskalah movement.

[1][3][5] Szwarc was a notable polyglot, speaking Russian, Polish, German, English, French, Italian, Spanish, Portuguese, Hebrew, and Yiddish, likely assisting him in his frequent work travels.

[1][3][5] When World War I broke out, making work in Western Europe impossible, Samuel and his wife decided to move to Lisbon, Portugal, as he had heard positive things about the country during his stint in Spain.

[6] In 1917 Schwarz's professional work as a mining engineer and his interest in crypto-Judaism led him to Belmonte in Portugal's northern Trás-os-Montes region.

[1][6] At the time the First Portuguese Republic enjoyed relative intellectual freedom, especially when compared to its successor the corporatist, semi-fascist Estado Novo regime.

Though the Jews of Belmonte were initially skeptical of Schwarz given their secrecy, he eventually gained their trust when he recited the Shema Yisrael prayer and uttered the name of God (Adonai), which they recognized.

[1][4] In the succeeding years Schwarz further befriended and studied Belmonte's Jewish community, documenting their unique social and religious customs and transcribing their prayers and family manuscripts.

[1][4] Seeing his studies of the Marranos as important to the wider Jewish community, Schwarz also published various articles in British, Spanish, French, Polish, and Italian magazines and newspapers regarding the matter.

[1][6][8] Though Samuel, Agatha, and Clara remained safe in Portugal during the Holocaust and World War II, they lost relatives on both the Szwarc and Barbasch sides of the family.

[3] Samuel tried without success to get some relatives to live in Portugal: the Portuguese government denied his requests to allow them to settle, though they transited through Lisbon en route to London in June 1940.

[5] Later in life Schwarz suffered from ill health, ultimately preventing him from visiting his surviving brothers, nieces, nephews, and other relatives who had settled in Israel and elsewhere.

[4] Though intended to stay in Tomar,[4] the collection found its way to the Portuguese Ministry of Finance's Historic Archive, where it sat in storage for decades.