Markus Szenwic was born on February 1, 1830 in Płock, in the family of Jakub Lewin and Jacheta. According to the consensus issued on August 19, 1861, he dealt in spices, small stalls, candles, soap, chocolate, leather, iron, cotton, linen, glass, mirrors, grain, stationery and herring. He was an elder of the merchants’ assembly of the city of Płock. The “Official Yearbook of the Kingdom of Poland for 1863” mentions him, next to e.g. Chaskiel Goldman, Icek Fogel and Szmul Neumark, among the deputy members of the Town Council of Płock. He was also a member of the Synagogue Supervision.
Markus Szenwic was the owner of several properties in Płock. After his father’s death, he inherited a house with a granary at Piekarska Street (mortgage number 88) and a property on the corner of Kolegialna and Tumska Streets (mortgage number 282). He was also the owner of a tenement house at 11 Old Market Square (mortgage number 21/416 and 17). His “Kantor Wexlu” company was located at this address.
Markus Szenwic was a supporter of the assimilation trend. “Known for his willingness to sacrifice”, he was actively involved in charity work. After the death of his father, together with his brothers Natan and Chaskiel, he donated nearly 2,500 rubles to the Jewish community, allocating this amount to the construction of a new hospital for members of the Jewish community of Płock. The hospital, named after Izaak Fogel, was opened in December 1872. In 1876, the Welfare Council of the Płock Governorate appointed Markus Szenwic as its curator (honorary guardian). The medical facility, located at Misjonarska Street, functioned until 1941.
In the autumn of 1879, Markus Szenwic became a member of the committee whose aim was to develop a project and raise funds to launch an inexpensive canteen for the poor Jewish population of Płock. He was also a member of the Chariy Society in Płock, approved on May 29, 1881, whose aim was to help the poor and limit the poor begging in the streets.
He died on February 14, 1894, in his own house at the Old Market Square.
Markus Szenwic was married twice. His first wife was Gitla (Augusta) née Ginsberg, with whom he had five sons: Jakub Lejb (1866-1927), Chaim Moszek Markus (Chrystian Moryc) (born 1854), Hersz (1869-1906), Majer (born 1874 ) and Izydor (1862-1930) and daughters Maria and Rozalia. With his second wife, Eloiza (Alicja) née Auerbach, Markus Szenwic had three children: sons Abram (1879-1914) and Georg (Gabriel) (born 1881) and daughter Klara (born 1887). Alicja Szenwic died in Trieste on September 18, 1931.
