
The frail 89-year-old arrived in Germany on Tuesday morning after being deported from the US.
He is now in Stadelheim prison, say prosecutors, where he will undergo a medical check and then have his pages-long arrest warrant read out to him.
He denies accusations that he worked as a guard in the Sobibor Nazi death camp.
Mr Demjanjuk, who settled in the US in 1952, says he was captured by the Germans in his native Ukraine during the war and kept as a prisoner of war.
US agents on Monday removed him from his family home in Ohio, and he was placed aboard a private jet which touched down at Munich airport on Tuesday morning.
He has been fighting deportation since charges were levelled against him in March, arguing that he is too frail to be moved.
But the US government, which secretly shot footage showing him walking without assistance, argued he was fit to travel.
An appeals court ruled that the removal could go ahead, saying it was satisfied that Mr Demjanjuk would be provided with adequate care.
‘Say nothing’
A spokesman for Munich prosecutors said Mr Demjanjuk had arrived at the Stadelheim prison, where he will stay in the medical unit.
He will first undergo a medical test to ascertain if he is fit to stand trial.
Mr Demjanjuk’s lawyer, Guenter Maull, said a duty judge would then open an arrest warrant against his client. The warrant, thought to be 21 pages long, would be read to his client in full in the presence of a translator.
Mr Maull said he would advise his client not to answer questions.
“I will put pressure on him not to say anything, because we need to talk in peace first and digest everything that is in the arrest warrant.
“It does not have to be correct just because it is written there,” he said.
Prosecutors, however, say they have documents which prove his Nazi background, including an SS identity card which shows he was posted to the death camp in Sobibor in 1943 and many witness testimonies.
Mr Demjanjuk’s deportation was welcomed by observers.
Wolfgang Benz, head of the Centre for Anti-Semitism Research at Berlin university, said the case was about establishing whether Mr Demjanjuk was guilty, not exacting punishment.
“This is about guilt, about avenging a crime, about responsibility for a criminal act,” he told told Deutschlandfunk public radio.
“Whether this old man who possibly is in a pathetic state spends his last years in a prison hospital or does not serve his sentence due to ill health, that’s of secondary importance.”
That opinion was echoed by Stephan Kramer, general secretary of the Central Consistory of Jews in Germany.
“I am not as naive as to believe that he [Demjanjuk] will spend even one day in prison. But we will get a discussion about justice in post-war Germany and how the justice system has dealt with Nazi crimes,” he was quoted as saying.
Citizenship stripped
Mr Demjanjuk arrived in the US in 1952 as a refugee, settling in Cleveland, Ohio, where he worked in the car industry.
In 1988 he was sentenced to death in Israel for crimes against humanity after Holocaust survivors identified him as the notorious “Ivan the Terrible”, a guard at the Treblinka death camp.
But Israel’s highest court later overturned his sentence, after documents from the former Soviet Union indicated that “Ivan the Terrible” had probably been a different man.
Mr Demjanjuk returned to the US, but in 2002 had his US citizenship stripped because of his failure to disclose his work at Nazi camps when he first arrived as a refugee.
In 2005, a US immigration judge ruled that he could be deported to Germany, Poland or Ukraine.
And in March 2009, prosecutors in Munich issued a warrant for his arrest, accusing him of being an accessory in the deaths of 29,000 Jews.