TORONTO — A retired German judge turned Nazi hunter was in Canada last week to gather evidence against a former Auschwitz guard about to go on trial.

Thomas Walther interviewed six Hungarian-born Auschwitz survivors in Toronto and was en route to Montreal, where he was slated to speak to at least two more.

The survivors came forward in response to a CJN article last summer on his efforts.

Walther, 71, found the Toronto testimonies credible enough to be submitted as evidence in the case against Oskar Gröning, who served as an SS guard at the death camp when thousands of Hungarian Jews arrived in the spring of 1944.

In Toronto, Walther also interviewed a woman who was eight years old at the time and who narrowly escaped the transport to the death camp, but whose parents did not.

In a CJN interview, Walther explained that under German criminal law, a close relative of a victim of violent crime who did not witness the crime, such as a sibling or child, can be a “co-plaintiff” in a case. Their testimony is comparable to a victim impact statement in Canadian courts.

The witnesses need not appear in a German court. Their testimonies will become part of the court record against Gröning, now 93, who in September was formally charged with 300,000 counts of aiding and abetting murder.

Known as “the Bookkeeper of Auschwitz,” Gröning was in charge of collecting the valuables and other possessions of Hungarian Jews between May 15 and July 12, 1944. In that time, 437,000 Jews from Hungary and neighbouring territories arrived by train at Auschwitz, and 300,000 were sent to the gas chambers right away.

Walther said all the survivors he interviewed in Toronto recalled the same thing: upon arrival after a disorienting ride several days long, they were greeted with shouts of “Raus, raus!” (Out, out!) and “schnell, schnell” (fast, fast!).

“These are the words I hear from the survivors,” Walther said. “They remember that.” And the barking of guard dogs.

But none of the Auschwitz survivors would have seen Gröning, who was in charge of the so-called Kanada Kommando – prisoners who did the actual collecting of luggage, jewelry, watches and cash, which was then transported to warehouses called Kanada.

“He had no direct contact with arrivals,” Walther explained. “He didn’t touch one piece of luggage.”

It was Gröning’s job to tally and catalogue all the booty and turn it over to the Nazi regime.

Gröning has spoken openly about his time as a guard and said that while he witnessed horrific atrocities and has been haunted by them, he didn’t commit any crimes himself.

Walther sees it another way.

Gröning “was one small cog in the killing machine. But all these small cogs had to work together in this factory of death.”

Walther served as a judge for 31 years. Instead of retiring in 2006, he joined the Central Office for the Investigation of Nazi Crimes, based in Ludwigsburg, Germany.

Testimony in the case against Gröning “helps visualize the meaning of the word Holocaust,” he said. “You can show the fences, the barracks, the gas chambers. But you cannot show the pain inside of the families. You cannot show the tears of the survivors. You cannot show the guilty feeling that ‘I am the last one of my family who lived.’”

Loved ones of victims, meanwhile, can impart to the court feelings of loss.

“They cannot prove that anyone killed their father, but they have the possibility to explain, ‘what it means to me, that I had lost my father.’”

Walther has a personal connection to these cases. His father, Rudolf, hid two Jewish families during the Kristallnacht riots in 1938 and later helped them get out of Germany.

It was Walther who breathed new life into the case against John Demjanjuk, the notorious “Ivan the Terrible,” who was sentenced to death by a court in Israel in 1988. The verdict was later overturned by Israel’s Supreme Court.

But in 2011, thanks to Walther’s efforts, a German court convicted Demjanjuk as an accessory to the murder of more than 28,000 Dutch Jews at Sobibor and sentenced him to five years in prison. He was released pending an appeal and died the following year at age 91.

Gröning’s trial is set to begin in February.