Auschwitz convictions have been few and far between

About 6,500 SS personnel are estimated to have worked at the Nazis' most infamous concentration camp, but few have ever faced trial for their roles at Auschwitz.

Oskar Groening, 93, a former Auschwitz guard, was convicted on July 15, 2015 of being an accessory to the murder of 300,000 people and was sentenced to four years in prison. The case tested the argument that anyone who served at a Nazi death camp was complicit in what happened there.

Canadians were among those who testified. 

Given Groening's age, the case might be one of the last war-crimes trials related to Nazi Germany.

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The scant number of people brought to justice for being part of Nazi death machinery has been called "an ongoing scandal of postwar history." Only 50 SS guards from Auschwitz have been convicted in German courts.

David Marwell, who conducted historical and forensic research in support of prosecution of Nazi war criminals, told CBC News the low numbers over the decades had more to do with the legal systems in Germany and elsewhere than with a lack of will.

"Domestic criminal law is a very ineffective weapon against state-sponsored mass murder," said Marwell, who is the director of the Museum of Jewish Heritage in New York City. 

"It shouldn't obscure the fact that there was effort by many good people to see justice done. They were hampered by the time and the tools they had at their disposal."

What follows are prominent instances when people faced trial for their roles in the deaths of more than one million people at the extensive series of camps known as Auschwitz.

Rudolf Hoess, commandant of Auschwitz 

Rudolf Hoess expanded Auschwitz during his 3½ years in charge there, and was so successful at perfecting mass killings that he was commended by his superiors as a "true pioneer in this field."

He organized the building of the Birkenau extermination camp, settled on Zyklon B as an efficient killer and did it all with a cool detachment before returning to his wife and children in their house on the camp grounds.

Hoess was arrested in Germany near the northern town of Flensburg in 1946 and put on trial by the Supreme National Tribunal in Poland during March the following year.  

Hoess denied nothing and was hanged outside an Auschwitz crematorium on April 16, 1947.

1st Auschwitz trial

Forty senior SS officials who worked at Auschwitz were put on trial in late 1947 at Krakow, Poland, with all but one convicted and more than half put to death.

The convicted included:

• Arthur Liebehenschel, Hoess's successor.
• ​Hans Aumeier, the deputy commandant.
• Maximilian Grabner, the camp Gestapo chief.

Each man was hanged.

People on trial in lesser positions such as guards, a driver and accountant received sentences ranging from life imprisonment to three years in prison.

Frankfurt Auschwitz trials

A series of trials in Auschwitz beginning in 1963 sought to convict people linked to Auschwitz under German law, unlike the war crimes tribunal of the first trial.

Twenty-two lower-level SS were charged and 18 found guilty. Sentences ranged from life to five years in prison.

Among the convicted was Wilhelm Boger, an SS staff sergeant at Auschwitz. He invented a torture device called the Boger swing, which involved hanging victims upside-down from an iron pole. He was sentenced to life imprisonment for murder.

According to the International School for Holocaust Studies in Jerusalem, the low number of people brought to trial may have been due to prosecutor Fritz Bauer, who was more concerned with revealing the system and structure of the camps than bringing specific people to trial.

Oskar Groening ... and more to come?

Groening's trial was the first to test a new line of German legal reasoning that has unleashed an 11th-hour wave of new investigations of Nazi suspects. Prosecutors argued that anyone who was a death camp guard can be charged as an accessory to murders committed there, even without evidence of involvement in a specific death.

In past years, German prosecutors decided not to pursue the case against Groening and other concentration camp 
workers, saying there was no causal link between their actions and the killings that occurred around them.
 
Prosecutors in Hanover disagreed, emboldened by the case of Ivan Demjanjuk, who in 2011 was convicted of being an accessory to mass murder despite there being no evidence of his having committed a specific crime while a guard at the Sobibor extermination camp.

There are currently 10 open investigations against former Auschwitz guards, and charges have been filed in two of those cases.. Eight former guards at the Majdanek concentration camp near Lublin, Poland, are also under investigation.