The 93-year-old, who is charged with 300,000 counts of accessory to murder, said he witnessed individual atrocities but did not acknowledge participating in any crimes.
Eva Kor, a survivor of the death camp, is scheduled to testify after Groening. Some 60 survivors and relatives from the U.S., Canada, Israel and elsewhere have joined the trial as co-plaintiffs, as allowed under German law.
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