Little distinction was drawn between members of Hitler's armed SS legions and ordinary Germans whose families had lived for centuries in places like Silesia, West Prussia and Pomerania that were wrested from German control by the wartime Allies in 1945.
About seven million fled Communist retribution or were shipped out in cattle cars, and an estimated two million perished.
Until the fall of Communism in Poland, attempts by the survivors and their descendants to seek justice for the brutal crimes they say were committed against Germans in 1945 and 1946 were dismissed as "revanchism."
But now they have begun to hope for a fair hearing. Some of the most serious charges concern Communist concentration camps in which German civilians were interned in Poland after the war.
In the most widely publicized case to come to light, the Polish authorities are investigating murder charges against Solomon Morel, a former secret police officer who served in the Communist resistance during the war. In the spring of 1945 he was put in charge of what had been a Nazi concentration camp at Swietochlowice, near Katowice.
Mr. Morel, who is Jewish, lost both parents and his two brothers during the war. Witnesses at the camp he commanded after the war have charged that he had hundreds of German civilians tortured and beaten to death, and killed some himself.
The camp was dissolved in late 1945 after outbreaks of typhus.
After the end of Communist rule in Poland, Mr. Morel appeared at a hearing of the Commission on Crimes Against the Polish Nation in Katowice, where he denied the accusations of murder and torture and blamed typhus for the deaths at the camp. But he fled to Israel in 1993 and now lives in Tel Aviv with his daughter.
One of his accusers is Gerhard Gruschka, 64, a retired schoolteacher who lives in northern Germany and to this day says he does not understand why the Polish authorities arrested him on April 3, 1945, when he was not yet 15.
"Morel was 25 to 30 years old in 1945, of quite powerful build and, as I recall, driven by burning hatred," Mr. Gruschka said in a deposition. "When he picked out a prisoner for individual treatment, it usually amounted to a death warrant.
"His 'specialty' was to take the heavy stools left over from the German concentration camp equipment by the feet and beat the prisoners as hard as he could with the thick seats. Again and again after such raids, badly wounded prisoners had to be taken to the camp hospital, and some, with their heads smashed in, to the mortuary."
Dorota Boreczek, a Polish woman imprisoned in Swietochlowice in February 1945 with her German mother, said, "I was only 13 years old, and I saw people dying like animals there."
She now lives in Germany and is trying to raise money for a monument to the camp's victims.
Annelies van Calsteren, whose Dutch husband, Eric, survived a brutal beating (not at Mr. Morel's hands) in the camp when he was 15, said her husband had apparently been arrested because he had blond hair and blue eyes and spoke German. He gave a deposition to the German authorities before he died last year in The Hague, but it was returned to his widow because the Germans said they did not know where Mr. Morel was.
"I don't want him to be in jail, but I feel I cannot lay down what my husband started," Mrs. van Calsteren said.
Some of these victims feel uneasy about accusing a Jew of seeking revenge for what Germans had done.
"Only a few people even knew he was Jewish," said Joseph Jendryschik, who has been gathering information on the Swietochlowice camp since his father died there 49 years ago. "It doesn't matter if he was Christian or Muslim -- what matters is that he be brought to justice."
For Sigmund Karski, a journalist working for the powerful Silesian exile lobby in Bonn, the fact that Mr. Morel and other secret police officers recruited by the Communists after the war may have been Jews is irrelevant.
"It's only an alibi for Poles or Germans who want to try to excuse what they did during the war by saying the Jews were no better than they were," he said. "It's absurd to make the claim that most of the Polish Communist secret police were Jews. There weren't that many Jews left in Poland after the war."
John Sack, an American journalist, interviewed Mr. Morel and 23 other high-ranking Jewish members of the Office of State Security, the Polish Communist organization that kept some of the former Nazi concentration camps going under Soviet supervision after the war.
Mr. Sack asserted in his book "An Eye for an Eye" (Basic Books, 1993) that Stalin deliberately put Jews in charge of secret police activities in the formerly German territories.
But, Mr. Sack wrote, most of the Jewish officers in the organization, known by its Polish initials as U.B., left in disgust or were soon discharged. Mr. Morel, however, stayed in prison administration for 24 years, he said, before being purged by the Communists in 1968.
American critics have attacked Mr. Sack's book as sensational and its charges inadequately attributed to sources, but the writer said in a telephone interview that his extensive research left little doubt that Jews ran the Swietochlowice camp "from the bottom to the top."
"It pains me as a Jew to report this," he said.
Mr. Gruschka said he had written to Mr. Morel in Israel, urging him to take responsibility for the crimes at the camp. "It would be terrible for me if he, too, like so many of the Nazis, showed no repentance," Mr. Gruschka said.
Dr. Stanislaw Kaniewski, the senior prosecutor currently investigating Mr. Morel in Katowice, said in a telephone interview, "We suspect that he won't come back to Poland."
"No formal charges have yet been raised against him," Dr. Kaniewski said, "but the investigation is still active, and a large number of witnesses have testified." But he added that Poland had no extradition treaty with Israel and could not force Mr. Morel to return against his will.
Those who have seen him recently say he is now 75 and not in good health. His daughter, reached in Tel Aviv, relayed to him a request for an interview but said her father had refused.
Like the other Germans interviewed for this article, Mr. Gruschka denied that he was motivated by any desire to mitigate the seriousness of German war crimes.
"I have never been interested in 'tit for tat,' Mr. Gruschka said. "I know that the crimes committed by Germans came first, and were far worse. But I could never understand why the postwar concentration camps in Poland have always been swept under the carpet here, until now."
Photos: Gerhard Gruschka, shown in his garden in Balve, Germany, was imprisoned in a Communist concentration camp from 1945 to 1946. He is one of those accusing Solomon Morel of torturing and killing German civilians. (Karin Hill for The New York Times); Solomon Morel in 1945, when he commanded a former Nazi concentration camp near Katowice. Map of Poland showing location of Swietochlowice.