One of the last remaining Nazis to be tried for war crimes died last week before he was able to start serving his sentence. He was 96.

Oskar Groening, known as the "bookkeeper of Auschwitz," was sentenced to four years in prison after being convicted of accessory to murder in 2015. His four-year sentence was delayed due to health problems and court appeals. Groening was found guilty of accessory to the murder of 300,000 people at Auschwitz-Birkenau, Nazi Germany's most infamous death camp. More than 1.1 million people, most of whom were Jews, were murdered in the gas chambers at Auschwitz during World War II.

Groening's story is unusual among former Nazis, however. He sparked the attention of German authorities when he spoke out against Holocaust deniers in the 1980's, though he maintained he was merely "a cog in the gears" of the Nazi's attempted extermination of European Jews. "I would like you to believe me. I saw the gas chambers. I saw the crematoria. I saw the open fires," Groening said in a 2005 BBC interview. "I would like you to believe that these atrocities happened because I was there."

Groening's role at Auschwitz was to count the cash and document belongings of prisoners who were brought to the camp to be exterminated in the gas chambers. Since breaking his 60-year silence, Groening expressed remorse over his actions. "I ask for forgiveness," Groening told the judge during his trial. "I share morally in the guilt but whether I am guilty under criminal law, you will have to decide."

Of the more than 6,500 Nazi officers who worked at Auschwitz during the Holocaust, fewer than 50 were tried and convicted of crimes. Because so few Nazis were ever held accountable for their roles in the mass murder of more than 6 million Jews, Groening's trial is both legally and symbolically significant for Germany.

Reactions on social media, were, unsurprisingly, emotional.

For SS officers during the Holocaust, following orders was a matter of life and death. Insubordination was not tolerated, and those who refused an order by a superior were usually shot on the spot, though occasionally they faced a court marshal.

His outspoken admissions of guilt and remorse have not gone unnoticed.

Eva Kor was a victim of medical experiments performed on herself and her twin sister at Auschwitz by Dr. Josef Mengele, better known as "the angel of death." Kor was the only member of her family to survive. Currently living in Indiana, Kor emigrated to the United States after the war and worked as a real estate agent. She has spent much of her life sharing her story and has admirably, and bravely, offered forgiveness not only to Groening, but to Mengele as well. Kor also founded the Candles Holocaust Museum and Education Center in Terre Haute, Indiana, in 1995. It's mission is to ensure that the horrors of the Holocaust and the memories of those lost are not forgotten.

It is of utmost importance to remember that millions of victims and their families will probably never feel a sense of justice for the atrocities committed during World War II.