Stephen Sandor came to know about Don Bosco through the Salesian Bulletin, and immediately felt attracted to the Salesian charism. In 1936 he was accepted at the Clarisseum in Budapest where he did a two year aspirantate. He attended courses in printing technology at the Don Bosco Press. He began his novitiate but had to interrupt it as he was called to military service. In 1939 he was able to take up his novitiate again and eventually made his first profession on 8 September 1940 as a Salesian Brother.

He was assigned to the Clarisseum, and was actively involved in vocational education. He was also an assistant at the oratory and promoted the YCW (Young Catholic Workers). At the end of the Second World War he began working for the material and moral rebuilding of society, giving special attention to poor youth. His interest was in gathering them up and teaching them a trade..

In 1949 the State confiscated all ecclesiastical goods and began persecution of Catholic schools. Bro. Sandor tried to save what could be saved. Almost overnight religious found themselves reduced to nothing and had to disband. Stephen Sandor had to leave his printing operations - which had gained recognition - and "disappear", but instead of fleeing to the West he stayed in the country so he could keep working for Hungarian youth. He managed to find employment in a detergent factory in the Capital, and fearlessly but clandestinely kept up his apostolate, while knowing that it was a strictly forbidden activity. In July 1952 he was taken into custody at his workplace and was never seen again by his confreres. An official document shows that he was condemned to death and hanged on 8 June 1953.

"Let us give thanks to God for this gift of the Church to the Salesian Family during the Year of Faith", Fr Pierluigi Cameroni, Postulator General for the Salesian Family, said. "The new martyr, Stephen Sándor, a Salesian Brother, is a shining witness and intercessor who followed in Don Bosco's footsteps by offering the young the Gospel of joy through a pedagogy of kindness and by giving his own life. Let us be grateful to Pope Francis for this special gift.