The renewed probes of death camp guards come after the case of former Ohio autoworker John Demjanjuk, who died last year while appealing his 2011 conviction for accessory to murder after allegations he served in Sobibor.
His case established that death camp guards could be convicted as accessories to murder, even if there was no specific evidence of atrocities against them.
Bruins, however, had long been on the radar of German legal authorities and already served time in the 1980s for his role in the wartime slaying of two Dutch Jews.
Bruins was also already convicted and sentenced to death in absentia in the Netherlands in 1949 in a case that involved the killing of the resistance fighter.
The sentence was later commuted to life in prison, but attempts to extradite him were unsuccessful because he had obtained German citizenship through a policy instituted by Adolf Hitler to confer citizenship on foreigners who served the Nazi military.
Ulrich Sander, spokesman for an organization representing the victims of Nazi crimes, told the dpa news agency that the decision to bring Bruins to trial again, even at his advanced age, was a good one.
"We must make it clear for the future that such crimes are always prosecuted, that murderers never get away," he said.
Despite his age, Bruins was found medically fit to stand trial, though Kniffka said the stress of the proceedings against him has weakened him.
Trial sessions are being limited to a maximum of three hours in deference to his age and health.
Bruins volunteered for the Waffen SS, the combat arm of the Nazis' fanatical paramilitary organization, in 1941 after the Nazis conquered and occupied his homeland. He eventually rose to the rank of Unterscharfuehrer roughly equivalent to sergeant.
He fought on the eastern front in Russia until 1943 when he became ill and no longer fit for combat duty.
Transferred back to the Netherlands, he served first in the Sicherheitsdienst the Nazi internal intelligence agency and then the Sicherheitspolizei, or Security Police, in a unit tasked to find resistance fighters and Jews.
As part of that unit, he is accused of killing resistance fighter Aldert Klaas Dijkema in September 1944 in the town of Appingedam, near the German border in the northern Netherlands.
If convicted, he faces a possible life sentence.
Dijkema was apprehended by the Nazis on Sept. 9, 1944, on suspicion he was involved in the Dutch resistance.
According to prosecutors, Bruins and alleged accomplice August Neuhaeuser, who has since died, drove Dijkema to an isolated industrial area where they stopped and told him to "go take a leak."
As he walked away from the car, they fired at least four shots into him, including into the back of his head, killing him instantly, according to the indictment.
Bruins and Neuhaeuser reported that Dijkema was shot while trying to escape.
Though it is not clear who fired the fatal shots, under German law if both suspects were there with the intent to kill, it does not matter who pulled the trigger, according to prosecutors.
The trial is scheduled until the end of September but it could be extended.
- AP
