[4] In June 1942, the Petris moved to the Grzenda manor house in Poland after Horst was appointed as a plant manager there.

[7] When four Jews were caught in the estate while trying to escape from a transport to a death camp, Horst told Erna and her female guest that "this was men's work, nothing that women should be concerned about."

He also participated in mass deportations, and the massacre of 15 Ukrainian farmers who were reported to have delivered food to partisans.

He also once indiscriminately bombed a Ukrainian village with grenade launchers after suspecting the citizens of supporting partisans.

On one occasion, Erna had her husband send three Ukrainian peasant women to Janowska concentration camp after they refused to work.

Erna also accompanied her husband on hunts for fugitive Jews, during which she personally killed four Jewish men.

[9] In September 1943, Erna was returning from a shopping trip in Lviv in her carriage when she came across six nearly naked boys (aged 6 to 12) crouching by the side of the road.

When Erna realized they were Jewish escapees, she calmed them, took them home, fed them and waited for her husband to return.

When Horst did not return after several hours, Erna took the children into the woods to a pit where other Jews had been buried, lined them up, and shot them one by one execution-style.

[9] Horst and Erna both avoided detection during the initial search for war criminals in the post-war period.

Horst joined the Liberal Democratic Party of Germany, the Free German Trade Union Federation, and the Peasants Mutual Aid Association.

Asked why she did not talk sooner, she said she feared punishment, but thought her husband would take the blame for her crimes.

[11] Erna told the officers that she had learned how to best kill someone while overhearing her husband's colleagues discussing the mass shootings of Jews.

[12] In an audio recording of the trial, Erna was so open with the details of her crimes that the prosecutor cut her off and said "Thank you, we have heard enough".

However, he felt that Erna's husband was partly responsible for her behavior and that "the constant interaction with the SS beasts in Grzenda was a considerable factor in causing her to commit crimes."

Nevertheless, the evidence showed that Horst had not routinely abused and murdered people, but that he often did this on his own initiative, without direct orders.

[11] In letters to her attorneys, Erna wrote that the court interpreter had mistranslated the words of the foreign witnesses who testified against her, resulting in her being falsely implicated.

Becoming more desperate, Erna claimed that in 1938, around the time of Kristallnacht, she had protested the treatment of Jews, and that only her pregnancy kept her from being immediately arrested.

During her trips, she had visited the Janowska camp to select Jewish laborers and brought them back to her manor.

[11] On December 31, 1989, Erna was one of 46 Nazi war criminals convicted under East German law who were in prison.

[14] Although a West German court affirmed the verdict and sentence, Erna was released from prison on health grounds in 1992.

One account claims that Stille Hilfe, a relief organization for the SS, convinced a court to release her.

The organization was likely also responsible for her being invited to Bavaria, where she went on trips to the Alpine mountains and lakes with Gudrun Burwitz, the daughter of Heinrich Himmler and a prominent member of Stille Hilfe.

In an interview in 2006, Erna's daughter, who was 18 when her mother was arrested, said her parents had often showed the photo albums to her and special guests.