The trial of a 95-year-old former SS medic at Auschwitz has been suspended after a doctor found that he was unfit to be transported to court.

Hubert Zafke has been charged with being an accomplice in the murder of at least 3,681 people. Chief judge Klaus Kabisch put the proceedings on hold shortly after they opened on Monday, saying a doctor who examined the defendant on Sunday found that he had “suicidal thoughts and was suffering from stress reaction and hypertension”.

He was therefore “not in a state” to be transported to the court or to be heard, the judge said.

Prosecutors say Zafke was stationed on a path that led to the gas chambers and witnessed columns of prisoners being sent to their deaths. He would at the very least have been aware of the persistent clouds of smoke emitted from the crematorium chimneys and therefore must have known what was happening, they were set to argue.

Zafke’s ability to stand trial had long been a key contention. A first court had ruled against a trial, finding that he was suffering from dementia, before an appeals court overturned the decision.

The court has only set an initial two further hearing dates, 14 and 30 March. When he was first identified as a suspect last year, his son said: “My father is an elderly man. He has lived his life, so leave him in peace.”

Zafke’s trial, in the north-east town of Neubrandenburg, fits a mould of other recent cases against people allegedly involved in the apparatus of the Nazi death camps. The precedent was set in the case of John Demjanjuk, a guard at the Sobibor camp, who in 2011 was sentenced for being an accessory to the Holocaust even though it was not proved he had actually murdered anyone.

At previous trials of Nazis, starting with the Nuremberg trials of 1945, the onus was always on prosecutors to prove the accused’s direct involvement in atrocities. While the law has not changed, since the Demjanjuk trial it has been considered sufficient to pursue someone on the grounds that they were a cog in the apparatus, however small.

In what amounts to a judicial race against time to seize on the last opportunities to punish former Nazis before they die, Zafke’s trial is due to run at the same time as that of a former Auschwitz guard, Reinhold Hanning, 94, which opened in the western town of Detmold this month. He is accused of being an accessory to the murder of 170,000 people.

Last year in the northern town of Lüneburg, 94-year-old Oskar Gröning, the so-called “bookkeeper of Auschwitz” because of his role collecting prisoners’ possessions and taking the cash found in their luggage to Berlin, was sentenced to four years in prison after he was convicted of being an accessory to the murder of 300,000 people.

The sense of urgency in such cases is hammered home each day by the rate at which Holocaust survivors are dying, leaving ever fewer to give first-hand accounts of their suffering. A poignant reminder of that came this month with the death at age 93 of Samuel Willenberg, the last survivor of the Nazi death camp Treblinka.

The charges in Zafke’s case focus on a month-long period between August and September 1944 when 14 trains packed mainly with Jews from Poland, Slovenia, Greece, Germany and the Netherlands arrived at Auschwitz. In one of them was Anne Frank, the famous diarist, and her sister Margot, who were later transported to the Bergen-Belsen death camp, where they died in April 1945, probably of typhus.

Initially the judge appointed to Zafke’s case refused to allow Auschwitz survivors to give evidence, contrary to the custom in such cases, where witnesses have travelled from around the globe to deliver powerful testimony. But following the intervention of a higher court, she has been forced to relent.

“Survivors have been given the very strong impression that the Neubrandenburg judge adopted an arrogant position of denial towards Auschwitz survivors as co-plaintiffs and participants in the trial,” Christoph Heubner, executive vice-president of the International Auschwitz Committee, said on Thursday.

“Why the judge in Neubrandenburg chose such a different path to that of other similar trials in Lüneburg and Detmold is inexplicable to them,” he added.

He said the court now had the chance to emphasise that it was only too conscious of its responsibility to make up for “decades of deplorable failures by the German judiciary in accounting for SS crimes in German concentration camps and death camps”.

For decades SS guards were able to escape justice. Of 6,500 SS members who are known to have served at Auschwitz, only 29 were ever brought to trial in Germany. In the former communist East Germany, 20 were prosecuted. Most escaped justice because of the belief that prevailed until recently that anyone who had served under the Nazis had been forced to do so by the regime, and therefore was not guilty.

If Zafke’s trial goes ahead, one of at least two witnesses will be Walter Plywaski, 85, a Polish-born US citizen, who survived Auschwitz but lost his mother and father there. At the end of the second world war Plywaski was one of about 10,000 survivors of the notorious Lodz ghetto in Poland.