The Polish Underground State imposed severe punishment to anyone found guilty of blackmail,  that is, any Pole
handing a Jew over to the Germans.  The warnings were printed in underground newspapers throughout Poland.  
The following is an excerpt:

" The Directorate for Civil Action communicates:   The Polish community, although itself a victim of
frightful terrorism, watches with horror and deep compassion the remnants of the Jewish population
in Poland being massacred by the Nazis.  The community has lodged a protest against this crime.....
[The Polish community]....gave such efficient assistance [to the Jews ...that the Nazis have now
published a proclamation threatening the death penalty to those Poles who help hide the Jews....The
Directorate for Civil Action warns that blackmail cases are being listed and will be punished with the
utmost severity, immediately as far as possible, and certainly in the near future."

The Underground government had an enormous influence over the attitude of the Polish people.  The majority of
Poles respected their directives. Some did not.  Those who were found guilty of blackmail were sentenced and
executed.  Each sentence and execution was announced by the Directorate in their official newspapers,
Rzeczpospolita Polska (RP), and the Biuletyn Informacyjny (BI)).

On September 15, 1943, the RP printed the following announcement:

"  By sentence of the special court in Warsaw, on July 7, 1943, Borys, alias Boguslaw, alias
Boguslaw Jan Pilnik, born on May 5, 1912, son of Aleksander and Felicjy Szolkowska, domiciled
in Warsaw, ulica Pierackiego 17, was sentenced to death and the loss of civic and public rights
for collaborating with Nazi authorities to the detriment of the Polish community and for denouncing
to German authorities, Polish citizens of Jewish nationality who were hiding from the Germans;  
also for extorting from his victims large sums of money under pretext of needing this money to
protect the persons hiding;  subsequently, after betraying them to the Germans, they extorted
from the families of his victims various possessions - allegedly to supply them to the arrested
person but which he appropriated to himself.    The sentence was carried out August 25, 1943.
                                                                                                     - Directorate for Civil Action "

Although it is impossible to reproduce entire lists of sentences and executions, here are a few examples printed in
the underground newspapers:

July 17, 1943 Jan Grabiec, a tailor from Krakow was sentenced to death for blackmailing Jews.  Sentence
was carried out July 17, 1943. (RP)

RP Issue # 18 (69)  November 1, 1943   Waclaw Noworol, a farmer from Lupnica Murowana, district of Nowy Sucz.

BI Issue # 49 (204) December 9, 1943  Tadeusz Karcz from Warsaw, and Antoni Pajor from Dobranowice.

RP Issue# 4 (76) March 26, 1944  Janusz Krystek, a laborer from Grabow, district of Wegrow-Sokolow, was shot.
March 9, 1944 Proclamation of death sentence of Boleslaw Szostak, platoon leader of Warsaw Police.

RP Issue# 5 (77) April 28, 1944 Jan Lakinski (Warsaw) was sentenced to death for tracking down Jews.
March 18, 1944 Civil Court of Warsaw imposed the death penalty on Antoni Pietrzak, corporal of State Police
of Warsaw, for collaborating with the Nazis in persecuting the Jews.  He was shot on March 17, 1944.

The process of investigating cases of blackmail was a very dangerous and complicated one.  Obtaining evidence
was difficult and sometimes almost impossible.  Investigations could not have been conducted openly because
Polish citizens were being subjected to constant Nazi surveillance. It was not possible to confront them.  In many
cases blackmailers who knew that they were under investigation by the Polish Underground would denounce their
accusers to the Germans, and asked for their protection.  Investigations had to be done with the utmost discretion
and caution.  There were many instances where blackmailers who had been sentenced, quickly disappeared and
changed their names to evade capture.

In these and many other cases, sentences were delayed, or eventually abandoned.  While the Polish Underground
did not eliminate the practice of blackmail, they did exert enough influence on the Polish population that its practice
was greatly reduced.