The aim of the paper is to recall one of the most interesting and outstanding Polish mathematicians, Józef Marcinkiewicz (1910-1940), on the centenary of his birth. It also aims to shed light on the tragic circumstances of Marcinkiewicz's death in the Katyn massacre. The presentation of Marcinkiewicz's life is based on reminiscences by people who knew him, which the author of the current paper obtained through correspondence or which were preserved at the Mathematics Archives of the Institute of Mathematics of the Polish Academy of Sciences in Sopot. The paper has also made use of materials from the Regional Archives in Lviv (Lvov) and the Central Archives of Lithuania in Vilnius). The assessment of Marcinkiewicz's scholarly achievements relied on testimony of Professor Antoni Zygmund, his teacher and, later, editor of his works. The publication of hitherto unknown documents and reminiscences will make it possible to preserve the memory of a most remarkable person that Józef Marcinkiewicz undoubtedly was.