BERLIN — The sole surviving member of one of Germany’s deadliest neo-Nazi terrorist groups was sentenced to life imprisonment on Wednesday, in the culmination of a saga that has shamed the country’s security services, strained its relationship with Turkey and fueled accusations of institutional racism.
After a trial in Munich that lasted more than five years, the group member, Beate Zschäpe, was convicted of 10 counts of murder, with additional counts of attempted murder, robbery, arson and belonging to a terrorist organization.
But her conviction and sentencing, almost 18 years after the group’s first victim was killed, seems unlikely to bring closure at a time when German politics have become more fractured and the national discourse more anti-immigrant.
The trial started before Germany accepted more than a million refugees and before a far-right party had won any seats in Parliament, let alone become the country’s main opposition.
Then as now, however, victims and their families said that the criminal inquiries and subsequent trial had not done enough to expose the group’s network of helpers, with the initial investigators far quicker to suspect people from immigrant backgrounds than to realize that they were being targeted by right-wing terrorists.
Four people who helped the group were sentenced alongside Ms. Zschäpe, receiving prison terms from 30 months to 10 years. One was a former official of a far-right party, Ralf Wohlleben, who helped the group get a gun.
But as the judges explained their verdict, protesters outside demanded that more people be held accountable.
Between 2000 and 2007, Ms. Zschäpe, Uwe Mundlos and Uwe Böhnhardt killed a police officer and nine people from Greek or Turkish backgrounds, mostly shooting workers at small businesses.
The court also found they had twice planted bombs in Cologne, a city in western Germany, wounding almost two dozen people, and carried out a series of robberies to finance their terrorist cell, which they called the National Socialist Underground, a reference to the Nazi party’s official name.
The police initially sought suspects for the shootings among immigrant groups, questioning members of the victims’ families. One task force was named Bosporus, for the strait in Turkey separating Asia and Europe.
German news media referred to the crimes as the “döner” murders because many of those killed had worked in shops selling Turkish-style roasted meat on a skewer.
The result was that the neo-Nazi terrorists went unobserved, unsuspected and relatively free to continue their killing spree.
Nor was it an official action that cracked open the case.
Mr. Mundlos and Mr. Böhnhardt killed themselves after a botched robbery in 2011. Ms. Zschäpe set fire to the apartment where they had been holed up, apparently to get rid of evidence, and walked into a police station a few days later. She has been in custody ever since.
Although Ms. Zschäpe appears never to have pulled the trigger, the judges found that she had been an integral part of the group.
Heinz Fromm, the head of the German domestic intelligence, resigned in 2012 over failures in the investigation into the group and the premature shredding of an internal document salient to the case.
In 2013, the president of the German Parliament offered an official apology to the victims’ families. Two federal parliamentary inquiries — and more than half a dozen state parliamentary inquiries — have examined the case.
Gamze Kubasik, the daughter of Mehmet Kubasik, a Turkish-born kiosk owner who was killed by the trio in the western city of Dortmund in 2006, said at a news conference on Tuesday, “The N.S.U. killed my father, but the investigators destroyed his honor.”
The Turkish foreign minister, Mevlut Cavusoglu, also called for further investigation, according to Turkish news media, raising the idea of an official conspiracy.
“Punishment of the top suspect and other suspects are not enough,” Mr. Cavusoglu was quoted as saying. “Who are behind these murders in the intelligence service, in the deep state? Which state institutions? They must be revealed and punished too.”
Turkey has been involved in the trial since before its beginning, which was delayed by a lawsuit demanding space in court for Turkish reporters. Eight of the 10 murder victims had Turkish roots.
The life sentence for Ms. Zschäpe, handed down by Munich’s highest state court, came with a judgment of “especially heavy guilt,” which bars her from seeking parole for 15 years. Her punishment is the most severe available to a German court.
After the sentence was read, a lawyer for Ms. Zschäpe announced that she would appeal the verdict.
Follow Christopher F. Schuetze on Twitter: @CFSchuetze.