DETMOLD, Germany — In many ways, it is fitting that Germany’s last trial of a former SS guard at Auschwitz played out far from the spotlight, in this pretty provincial town of 70,000.

It was from places like these — a rural corner of North Rhine-Westphalia, modern Germany’s most populous state — that the Nazis formed their bedrock, the millions of men and women who signed up to Hitler’s apparently triumphant cause and with little questioning executed its murderous maxims.

They were people like Reinhold Hanning, 94, who on Friday was sentenced to five years as an accessory to at least 170,000 deaths during his time as an SS guard at the Auschwitz-Birkenau camp, from January 1943 to mid-1944.

After World War II, Mr. Hanning was in British custody, and he was released in 1948 to live out his life in his hometown, Lage, six miles from Detmold. He said he never spoke about Auschwitz to anyone, not even to his wife, two sons and grandchildren.

His four-month trial yielded a brief, carefully crafted apology of sorts from him for being a member of “a criminal organization, which is responsible for the death of many innocent people, for the destruction of countless families, for misery, torture and sorrow on the side of the victims and their relatives.”

That apology fell far short of the reckoning sought by 57 co-plaintiffs, Holocaust survivors like Leon Schwarzbaum, also 94, who on the trial’s opening day in February urged Mr. Hanning to break his silence, since “we will both soon meet our maker.”

“His statement does not go far enough for me,” Mr. Schwarzbaum said as the trial neared its end. “He should have talked more about what he did, what he took part in, saw. I learned nothing.”

On that same day, I sat with Thomas Walther, the German lawyer most responsible for the recent handful of prosecutions — seven decades too late — of SS guards at Auschwitz-Birkenau, the death camp where more than one million people were killed — gassed, shot, hanged, injected.

After he retired as a judge, Mr. Walther went to work at Germany’s office for Nazi crimes in Ludwigsburg. For decades, German jurists had argued that prosecution of death camp guards was possible only if they could be tied to specific crimes. That was a corollary to the dilatory pursuit of war crimes prosecutions by a West German justice system that was riddled with lawyers and judges who were former Nazis.

Only last year was this failing clearly portrayed in a hit movie, “The State vs. Fritz Bauer,” which chronicled the lonely fight of the Frankfurt state prosecutor who instigated Germany’s only Auschwitz trials in the 1960s, and who tipped off Mossad that Adolf Eichmann was in Argentina.

Of approximately 6,500 SS guards who had worked at Auschwitz, only 29 people were tried in West Germany. (Twenty more were tried in the Communist East.)

Working with Eli Rosenbaum, an American investigator at the United States Justice Department, Mr. Walther reinterpreted German law to allow for the prosecution of John Demjanjuk, the Ukrainian-born American who was eventually extradited to Germany and sentenced in 2011 to five years in prison as an accessory to approximately 28,000 murders in the Sobibor death camp. He died the next year.

The Ludwigsburg office pursued other former guards, resulting in the trial and sentencing last year of Oskar Gröning, 95, and now of Mr. Hanning. Another two people have been charged, but ill health has made completion of their trials unlikely.

Another former Auschwitz guard died in April, just before his trial was to start in Hanau, near Frankfurt.

“Whether in 30 or 40 years these few trials will appear in political and juridical history as a footnote, or a real chapter, only the future will show,” Mr. Walther said.

Mr. Gröning, who had talked in interviews of his Auschwitz past a decade before his trial, and Mr. Hanning were typical of lower-class Germans who saw joining the SS as a way to rise, even shine.

“Many of the underlings came from the provinces,” Mr. Walther said, unlike city dwellers, students or employees at big firms, “who had a certain openness to the world.”

Openness to the world affected post-Nazi justice, too. At my first war crimes trial in Cologne, Germany, in 1980, many spectators were from France, where Serge and Beate Klarsfeld had led the fight to prosecute one of three former Nazis who were sentenced to six to 12 years for assisting in the deportation of 73,000 French Jews to Auschwitz.

En route to that sentencing, I encountered a middle-aged West German man who, like so many Germans still, refused to give his name, but knew that he resented foreign meddling.

“It just brings it all up again,” he complained. “If we did not have these trials, then foreigners might forget the Nazis.”

In 1981, I reported the end of the last big war crimes trial, of nine defendants who worked at the Maidanek death camp where 250,000 people were killed. After six years in court, Hermine Braunsteiner Ryan, who married an American man after World War II, was the only one sentenced to life.

The courtroom emptied out once the sentence was pronounced. Hours later, I was almost the last person left listening to the judges’ reasoning. It all felt thorough — West Germany working through its history, serving justice — but there was no escaping an impression of living a footnote.

My next encounter with war crimes trials came in the Soviet Union, in June 1986 in the Crimean capital, Simferopol.

Fyodor Fedorenko, a Ukrainian and the first war crimes suspect extradited from the United States to the Soviet Union, was on trial, accused of working for the Nazis in the Treblinka death camp. Hailing from the same region as Mr. Demjanjuk, Mr. Fedorenko received nothing like the thorough hearing of a German court.

His long-estranged peasant wife was produced, and suggested that Mr. Fedorenko had opposed Soviet collectivization. He was depicted as a willing servant of the invading Nazis. Soviet justice was summary: Pronounced guilty, he was executed.

The trial last year of Mr. Gröning, in another pretty, provincial town, Lüneburg, might have seemed unspectacular. Yet like all the others, it was a reminder of how 20th-century history marched through the lives of perpetrators and victims — and that we all always have choices, and make them.

Mr. Hanning’s choice was the SS. He was wounded in fighting around Kiev, wound up in convalescence at a facility used by Auschwitz guards — and then joined them, under circumstances not clarified by the trial.

Leonie Figge, 16, and Stina Ulbrich, 17, among 25 teenagers who had visited Israel in March, came to Mr. Hanning’s trial a few times. “I am so glad to have had the opportunity to be here,” Ms. Ulbrich said. “It simply moves you.”

They were avid to learn from Leon Schwarzbaum, who, like other Holocaust survivors and co-plaintiffs, regularly visits schools to pass on his experiences of the death camps. Ms. Ulbrich imagined in turn passing his words to her own children someday.

Perhaps that will be this trial’s most lasting achievement.

In the meantime, Mr. Walther and I sat in Detmold’s pristine old town, which has fine timberwork buildings. When the Nazis held sway in places like these, he reflected, “there were so many swastikas hanging that they covered all the beams.”