The story of Frank Walus is the story of "The Nazi Who Never Was":

In 1976 Simon Wiesenthal, in Vienna, had gone public with charges that a Polish emigre living in Chicago, Frank Walus, had been a collaborator involved in persecuting Polish Jews, including women and children, as part of a Gestapo-led auxiliary police unit.  Walus, charged Wiesenthal, "performed his duties with the Gestapo in the ghettos of Czestochowa and Kielce and handed over numerous Jews to the Gestapo."  (p. 193)

Walus, in turn, was convicted by judge Julius Hoffman, who

ran the trial with an iron hand and an eccentricity that bordered on the bizarre.  He allowed government witnesses great latitude, while limiting severely Korenkiewicz's cross-examination of them.  When Walus himself testified, Hoffman limited him almost entirely to simple yes and no answers.  (p. 193)

Despite weaknesses in the prosecution case, Judge Hoffman went on to convict Walus, and later despite accumulating evidence of Walus's innocence, refused to reconsider his verdict.  But

then a formal appeal was filed.  The process took almost two years, but in February 1980, the court ruled.  It threw out Hoffman's verdict and ordered Walus retried.  In making the ruling, the court said that it appeared the government's case against Walus was "weak" but that Hoffman's handling of the trial had been so biased that it could not evaluate the evidence properly.  (p. 195)

In view of irrefutable documentary and eye-witness evidence that Walus had served as a farm laborer in Germany during the entire war, he was never re-tried.  And what, we may ask, was the occasion for Simon Wiesenthal's fingering Walus in the first place?

Only later was the source of the "evidence" against Walus that had reached Simon Wiesenthal identified.  Walus had bought a two-family duplex when he came to Chicago.  In the early 1970s, he rented out the second unit to a tenant with whom he eventually had a fight.  Walus evicted the tenant, who then started telling one and all how his former landlord used to sit around and reminisce about the atrocities he had committed against Jews in the good old days.  Apparently one of the groups to which he told the story was a Jewish refugee agency in Chicago, which passed the information along to Simon Wiesenthal.  (p. 195)