[2] Following the postwar Soviet takeover of Poland he was arrested, accused of numerous crimes, and executed in Warsaw's Mokotów Prison as an anti-communist diehard soldier.

Szendzielarz was born in Stryj (Austrian Partition, now Lviv Oblast, Ukraine), then part of Austria-Hungary and from 1919 to 1939 in Poland, into the family of a railway worker.

He was promoted to lieutenant and transferred to Vilnius, where he assumed command of a squadron in the 4th Niemen Uhlan Regiment.With his unit, he took part in the 1939 September Campaign.

Soon afterwards Szendzielarz was taken prisoner of war by the Soviets, but he managed to escape to Lwów, where he lived for a short period under a false name.

He tried to cross the Hungarian border to escape from Poland and reach the Polish Army in France, but failed and finally moved with his family to Vilnius.

In mid-1943 he joined the Home Army under the nom de guerre Łupaszka, after Jerzy Dąbrowski,[3] and in August he started organizing his own partisan group in the forests surrounding the city.

By September, the unit was 700 men strong and was officially named the 5th Vilnian Home Army Brigade (5 Wileńska Brygada Armii Krajowej).

In reprisal actions, his brigade captured several dozen German officials and sent several threatening letters to Gestapo but it remains unknown if and how these contributed to his release.

[4] In reprisal, on 23 June 1944, a unit of 5th Vilnian Home Army Brigade attacked the fortified village of Dubingiai, capturing a bunker defended by Lithuanian policemen.

In what became known as Operation Ostra Brama, the 5th Brigade was to attack the Vilnius suburb of Žvėrynas in cooperation with advancing units of the 3rd Belorussian Front.

During a 2013 exhumation Szendzielarz's remains were recovered and identified as one of roughly 250 bodies buried in a mass grave at the Meadow at Warsaw's Powązki Military Cemetery.

Findings from the Polish Institute of National Remembrance (IPN) leave no doubt that the retaliatory action of the 5th Home Army Brigade was a war crime on civilians.