A witness at the trial of John Demjanjuk on Tuesday described his deportation in a crowded freight car to the Nazis' Sobibor death camp, where the retired auto worker is alleged to have been a guard.

Jules Schelvis, 88, is one of dozens of victims' relatives who have joined the trial as co-plaintiffs as allowed under German law. He told the Munich state court that he lost 18 relatives — including his wife, Rachel, at the camp in Nazi-occupied Poland.

SLIDESHOW: Alleged Nazi on Trial

Demjanjuk, a former Soviet Red Army soldier, is charged with 27,900 counts of accessory to murder for his alleged activities as a guard at Sobibor, for which prosecutors allege he volunteered as an SS guard after being captured by the Germans in 1942.

Now ailing with bone marrow disease, the 89-year-old Demjanjuk was brought into court on a stretcher and lay with his eyes closed through Tuesday's proceedings, with Schelvis due to testify through the afternoon.

During the morning session, Schelvis recalled boarding the last wagon in a 50-car freight train bound for Sobibor from the Dutch transit camp of Westerbork.

"There wasn't enough room to sit down" in the car, with 62 people inside, Schelvis said. He told the court there were no seats, just two barrels: one containing water, and an empty one used as a toilet. Occupants crowded together so that the old and sick could lie down.

Schelvis remembered having a guitar he had taken when he and more than 3,000 others were rounded up a few days earlier in Amsterdam's Jewish district, saying he had done "everything with the thought that we were being deported to work, otherwise I wouldn't have taken a guitar."

"They didn't tell us anything about where we were going," he said. "We just had to get on board."

Demjanjuk, who was deported from the U.S. in May, denies ever having served as a guard, saying he spent much of the war in Nazi POW camps before joining the so-called Vlasov Army of anti-communist Soviet POWs. That army was formed to fight alongside the Germans against the Soviets in the war's final months.

Defense lawyer Ulrich Busch has called for the case against Demjanjuk to be thrown out.

After a series of defense motions were rejected Monday, Busch unsuccessfully called Tuesday for a halt to proceedings before accusing the trial judges of bias and saying his client "has become the victim of an international judicial plot."

Cornelius Nestler, a lawyer for co-plaintiffs, said the defense motions were reminiscent of a tape that constantly repeats itself — "and the arguments don't get better."

Demjanjuk had been extradited in the 1980s by the U.S. for trial in Israel on charges that he was the brutal guard at Treblinka nicknamed "Ivan the Terrible." He was convicted in 1988 of war crimes and crimes against humanity, and spent seven years in prison until Israel's Supreme Court overturned the conviction in 1993 — ruling that another person was "Ivan the Terrible."