Auschwitz convictions have been few and far between

About 6,500 SS personnel are estimated to have worked at theNazis' most infamous concentration camp, but fewhave ever faced trialfor their roles at Auschwitz.

OskarGroening, 93, a former Auschwitz guard, wasconvicted on July 15, 2015 of being an accessoryto the murder of 300,000 people and was sentenced to four years in prison. Thecase 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 mightbeone of the last war-crimes trials related to Nazi Germany.

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The scantnumber of people brought to justice for being part of Nazideath machinery has beencalled "an ongoing scandal of postwar history." Only 50SS guards from Auschwitz have been convicted in German courts.

David Marwell, whoconductedhistorical and forensic research in support of prosecutionof Nazi war criminals, told CBC News the low numbers over the decadeshad more to do with the legal systems in Germany and elsewherethan with a lack of will.

"Domesticcriminal law is a very ineffective weapon against state-sponsored mass murder," said Marwell, who isthedirector of theMuseum of Jewish HeritageinNew York City.

"It shouldn't obscure the fact that there was effort by manygood people to see justice done. They were hampered bythe 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 Hoessexpanded Auschwitzduring his 3years in charge there, and was sosuccessful at perfecting mass killings thathe 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 intheir house on the camp grounds.

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

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

1st Auschwitz trial

Fortysenior 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 oftrials in Auschwitz beginningin 1963sought to convict people linked toAuschwitzunder German law, unlike the war crimes tribunal of the first trial.

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

Among the convicted was WilhelmBoger, an SS staff sergeant at Auschwitz. He invented a torture device called the Bogerswing, which involved hanging victims upside-downfrom 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, Germanprosecutors 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 Sobiborextermination camp.

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