Hamburg, Germany — Bruno Dey was 17 years old when he joined the unit Death's Head unit of Adolf Hitler's SS, the division tasked with running Nazi death camps. On Thursday, now 93, Dey faced the first day of his trial on charges of being an accessory to more than 5,000 murders. It could be the last trial of its kind in Germany, as Dey is one of the few Nazi suspects still alive who could be charged over their actions during the Holocaust.

Between August 1944 and April 1945, Dey served as an SS guard in Stutthof concentration camp, 24 miles east of the Nazi-occupied Polish city of Gdańsk.

On Thursday, 73 years after he last guarded a watchtower at what was the Nazis' first death camp outside German borders, Dey was accused of being an accessory to the murder of 5,230 prisoners.

The Nazi's Stutthof concentration camp in Poland is seen in a 1941 file photo provided by the Stutthof Museum in Sztutowo, Poland. Stutthof Museum

That number includes 5,000 people who died of typhoid in horrifically unhygienic conditions, but he is also implicated in the execution of 200 people gassed with Zyklon B, and 30 more who were shot in the neck.

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The American plaintiff

A recent portrait of American Judy Meisel, who escaped from the Nazi's Stutthof death camp in Poland, provided by David Sherman for "Transfer of Memory." David Sherman

Judy Meisel is one of the 20 co-plaintiffs in the case against Dey. She witnessed the atrocities carried out by the Germans in Stutthof. Together with her mother and her sister Rachel, she was sent to the concentration camp from her native Lithuania in 1941 after Hitler's forces invaded.

"Her mother was murdered in the gas chamber," Meisel's grandson Benjamin Cohen told CBS News on Thursday after watching the trial begin. "They were tortured, her hair was ripped out by two SS men when they arrived at the camp. It was total brutality."

Meisel is now an American citizen and lives in Minnesota. She couldn't travel to Germany for the trial for health reasons.

She and her sister both managed to escape from Stutthof. Her grandson has vowed to tell her story, and he hopes to hear Bruno Dey's side of the story, too, to get an answer to the question his grandmother has longed for.

"How could they do this? How could someone be a part of that?" he said. "Her lesson is the power of the human spirit, to come out of it not hateful and not looking for revenge."

Judy Meisel (left) and her sister Rachel in Denmark after escaping from the Nazis' Stutthof concentration camp in Poland. Courtesy of Ben Cohen

Tried as a minor

Because Dey was under the age of 18 at the time of the alleged crime, he is being tried at the juvenile court in Hamburg. If convicted, he faces up to 10 years in jail, but it's unlikely he'll serve any prison sentence due to his old age and physical condition.

Dr. Efraim Zuroff, who represents the Simon Wiesenthal Center and who has dedicated his life to tracking down and delivering ex-Nazis to justice, told reporters on Thursday that while Dey "might look weak, he's probably trying to look as sick as possible, but when you look at him, think of him as a young man at the height of his physical powers who devoted all of his energies to mass murdering innocent civilians."

93-year-old former SS guard Bruno Dey covers his face as he arrives at the courtroom in Hamburg, October 17, 2019. Getty

Dey gave no statement on Thursday but promised to do so in future sessions. He covered his face with a red folder as he entered the courtroom in a wheelchair, accompanied by his wife, daughter and other relatives who sobbed in the corners of the room.

Trying accessories to Nazi murder

Dey's defense lawyer Stefan Waterkamp presented a brief testimony from his client, who denounced the German judiciary for acting on the basis of newly implemented laws. Dey has testified before; he gave statements to the police in 1975 and again in 1982, but faced no further consequences.

Since the 2011 sentencing of John Demjanjuk, a Ukrainian POW who became a Nazi collaborator, the criminal justice system in Germany has opened multiple cases against former Nazi personnel. The trial against Demjanjuk set a new precedent, allowing suspects to be tried as accessories to the Nazi killing machine even if they didn't commit individual murders.

In Dey's case, the prosectors argue that he played a crucial role in Stutthof's mass killings as he stopped prisoners from escaping the camp. Before its liberation in April 1945, some 65,000 people were murdered at the camp, 70% of them Jews.

Dey has given testimony to German police eight times. According to German newspaper Die Welt, he confessed to knowing what was happening inside the gas chambers.

"I probably knew that these were Jews who hadn't committed a crime, that they were only in here because they were Jews, and they have a right to live and work freely like every other human being," he reportedly told the investigators.

After the first day of the trial, Zuroff told CBS News that Dey and the other former Nazi camp staff were "the last people who deserve sympathy in the world."