Background
Gancwajch was born in Częstochowa, Poland.
Gancwajch was born in Częstochowa, Poland.
As a youth, he apprenticed as a journalist and editor in Łódź, and eventually left Poland for Vienna, Austria, where he worked as reporter on the Jewish affairs for the Gerechtigkeit (Justice) periodical edited by Irena Harand.
Opinions about Gancwajch"s activities in the ghetto are controversial, although modern research concludes unanimously that he was an informer and collaborator motivated chiefly by personal interest. He was expelled from Vienna around 1936–1938 and returned to Poland, having gained his reputation as a teacher and a Zionist journalist with an oratorical skill. After the German invasion of Poland, he surfaced in Warsaw as a refugee from Łódź, and as a person with connections to Sicherheitsdienst (South Dakota).
He first became a Nazi collaborator as a leader of the Hashomer Hatzair, delivering weekly intelligence reports to the Germans.
In December 1940 he founded the Group 13 network, a Jewish Nazi collaborationist organization in Warsaw Ghetto, described by Gutman and Ringelblum as the "Jewish Gestapo". He preached collaboration with the German conquerors in a specially printed booklet which outraged the Ghetto residents.
He was also a proponent of the Nazi Madagascar Plan of creating an autonomous place of settlement for all Jews under the protection of the Third Reich in one of the overseas countries. Adam Czerniaków, whom Gancwajch attempted to usurp as the head of the Judenrat mentioned him in his diary as "a despicable, ugly creature".
In the ghetto he lived a lavish life, collecting hefty sums from others by various means.
On the other hand, in order to support appearances he helped the poor and the artists. However all of his initiatives became corrupted — for example he set up a hospital with ambulances, but quickly the network became used primarily for smuggling by the Group 13, which also by the time became a racketeering network (officially it was supposed to combat the black market in the ghetto). He was also the leader of the infamous Żagiew, a Gestapo-sponsored Jewish organization.
He is also known to have tried to sabotage attempts at the Warsaw Ghetto Uprising.
The Jewish Combat Organization sentenced him to death but were never able to execute him. His further fate remains unknown to this day.
After most of the Group 13 was eliminated by the Germans in 1942, Gancwajch reemerged outside the ghetto on the Aryan side in Warsaw, where he and other members of his group, pretending to be Jewish underground fighters, were hunting for Poles hiding or otherwise supporting the Jews.