The conviction of John Demjanjuk, 91, by a German court is significant in many respects, not the least of which is that this may be one of the last Nazi war crimes trials.

Demjanjuk was found guilty of having been an accessory to the murder of more than 28,000 Jewish men, women and children at the Sobibor extermination camp, having been trained at the Trawniki camp in Nazi-occupied Poland. He was convicted primarily on the basis of documentary evidence, records of his service at several camps, including his identification card from the Trawniki camp. At the trial, relatives of those murdered at Sobibor during the time Demjanjuk served there, confirmed their place on the train transports that took them to their deaths. Demjanjuk was sentenced to five years in jail and was released pending appeal.

By trying Demjanjuk, who was born in Soviet-era Ukraine and served the Germans in Nazi-occupied Poland, Germany makes the point that its moral and legal responsibility for trying crimes of the Nazi era does not end at Germany’s present borders, and that the Germans recruited willing non-German participants to aid in the murder of the Jews, who bear responsibility for their actions.

Judge Ralph Alt, who presided at the trial, was quoted as saying “Every Trawniki man knew that he was part of a well and smoothly operating apparatus that had no other goal than systematically murdering Jews. They all knew about the barbaric treatment of Jews. And the accused was part of that extermination machinery.”

This is the latest, but possibly not the last, chapter in the Demjanjuk saga, which reaches back to the mid-1970s, when Demjanjuk, then an immigrant Cleveland auto-worker, was first accused of being a former Nazi guard. Trials ensued in the United States, stripping him of his citizenship, ordering him deported, and then extradited to Israel, where he was prosecuted in the late 1980s in a public trial that sought to prove that in addition to serving at Trawniki and Sobibor, he was also the sadistic gas chamber operator at Treblinka, called “Ivan The Terrible.”

When, on appeal, testimonies from the former Soviet Union pointed to another person being the gas chamber operator at Treblinka, Israel’s Supreme Court ordered the release of Demjanjuk, based on reasonable doubt, and although it was affirmed that he was at Trawniki and Sobibor, Israeli courts declined to hold or retry him on those charges — a decision that was seen as speaking to Israel’s fairness. Back in the United States, the government was forced to begin its case anew, once again denaturalizing Demjanjuk, and ordering him deported to Germany. And that is where he has now been tried and convicted.

The persistence of the governments of the United States (throughout both Republican and Democratic administrations), Israel, and Germany in pursuing this case over the years is to be commended. Throughout it all, Demjanjuk has sought to deny his involvement, and at each turn the evidence and the courts have put truth to his lie. When they found a criminal before them, they prosecuted him.

Demjanjuk has been sentenced to five years in prison, taking into account his age, his prison time in Israel and the fact that having been denaturalized of his United States citizenship, he was separated from his family. Given his advanced age, and the fact that the appeals on his behalf could take up to a year, there is some question as to whether Demjanjuk will ever enter prison. The German prosecutor is considering appealing the decision to release Demjanjuk.

Has justice been served with this mere five-year sentence (even for someone aged 91)? Is the fact that Demjanjuk is currently free on appeal in Germany justice? Is this a fitting, or even satisfying, end to the decades-long prosecution of a participant in the murder of thousands of Jewish men women and children?

I am still struggling with this odd calculus of German crime and punishment but only time will tell how this story ends – the last page is still not written. However, I can still recall sitting in the courtroom in Jerusalem more than two decades ago, watching Demjanjuk for many days on end. The crimes described seemed to have taken place on another planet. Yet here before us was the tangible evidence, the documents, the records, the witnesses from that place. Here was another generation standing in court to say that a nation of laws trumps a nightmare of evil. The verdict today affirms that.

We live in a time when opinions are often taken as facts and when the torrent of commentary online in real time can overwhelm. Demjanjuk’s attorneys and supporters will continue to proclaim his innocence or denounce the evidence as forgeries.  But as of today, Demjanjuk once again bears the mark of Cain, as his guilt has been pronounced in a legal process carried out by German authorities in a courtroom in Munich – the very city where Hitler founded the Nazi party.

If the Nazis or their henchmen thought the world would forget their crimes, or not care, they have been proven wrong once again.

Mr. Teicholz is author of “The Trial of Ivan the Terrible: State of Israel Vs. John Demjanjuk,” which was issued by St. Martin’s Press in 1990.