Mazurkiewicz was born in 1911 and lived in Krakow. He was well dressed, well spoken and well connected, kept a car when almost nobody did, and was known around the city as a man who could arrange things. The Polish press called him the gentleman murderer.
Through the late 1940s and into the 1950s people who came to him, wanting foreign currency exchanged, papers obtained, or property sold, disappeared. He shot them, usually at close range, and took what they had brought with them. In a country of shortages and internal travel restrictions his standard of living was itself conspicuous, and it was funded this way.
He was arrested in 1956. He was convicted of six murders and of further attempts, and hanged at the Montelupich prison in Krakow on January 31, 1957.
The range of six to thirty in this roster is the difference between the convictions and the number of disappearances attributed to him in Krakow across that decade. The larger figure has never been substantiated and the entry does not adopt it.
The case is among the best known in postwar Poland, partly for the contrast between the man and the crimes, and partly because of what it says about the period: people who needed something done outside the official system had to deal with whoever offered, and had no way of checking him.