BERLIN - Former Nazi death camp guard John Demjanjuk, sentenced to five years in a German prison last year in one of the last major trials of its kind, has died at the age of 91, police said Saturday. The Ukrainian-born Demjanjuk had been found guilty of more than 27,000 counts of accessory to murder during the six months he was a guard at the Sobibor death camp in 1943. The ailing Demjanjuk was sentenced by a Munich court in May 2011 after a trial lasting 18 months.  However he was allowed to go free pending an appeal before a federal court, having already spent nearly two years in prison, on the grounds that he was not a threat and was unlikely to abscond, being stateless.

Police in the southern state of Bavaria said he died in a home for the aged in the town of Bad Feilnbach, adding that prosecutors would now conduct a routine investigation into the cause of death.

While there was no irrefutable evidence of his presence or actions at Sobibor in German-occupied Poland, the German court said in a landmark ruling that it was convinced he had been a guard, and was thus automatically implicated in killings carried out there at the time, mainly of Dutch Jews.

The US Office for Special Investigations (OSI), which investigates Nazi criminals, described Sobibor as “as close an approximation of Hell as has ever been created on this Earth.”

An estimated 150,000 to 250,000 people were exterminated there.

Demjanjuk had vigorously denied the charges and appealed his conviction, arguing throughout the proceedings that he had been a victim of the Nazis as a prisoner of war, not a perpetrator.

He went to live in the United States after the war, raising three children there. But in 1986, he was hauled before a court in Jerusalem accused of being “Ivan the Terrible,” an infamous Ukrainian guard at the Treblinka death camp.

Found guilty of all charges and sentenced to death in 1988, he was freed five years later when evidence surfaced proving Israel had got the wrong man.

After new indications emerged that he served as a guard at other Nazi camps, he was stripped of his US citizenship in 2002 for lying about his war record on immigration forms.

Years of legal wrangling ensued and he was deported from the United States to Germany in 2009 to again face trial, this time in Germany.

Because of ill health, Demjanjuk attended much of his trial either in a wheelchair or lying on a hospital bed, wearing dark glasses and a baseball cap.

He rarely spoke during the proceedings, which were limited to two 90-minute hearings per day so as to not overtax him.

After his conviction, the two dozen co-plaintiffs in the trial — relatives of those murdered at Sobibor — expressed regret that Demjanjuk never showed remorse.

Based on the precedent set by the Demjanjuk case requiring a less rigid standard of proof, the Nazi-hunting Simon Wiesenthal Centre launched a new drive in Germany in December to catch the last perpetrators of the Holocaust.

The organisation said it would offer an up to 25,000-euro ($32,900) reward for information leading to the capture and conviction of other elderly people implicated in Nazi crimes during World War II who are still at large.

Richard Prasquier, the president of CRIF, the umbrella group of French Jewish organisations, said the German authorities’ pursuit of Demjanjuk to the last had been justified.

“A number of guards did the dirty work for Germany,” he said.

Considering the horrors of the Holocaust, “it is only normal that we try to track down those responsible — it is not relentlessness, it is simply because the extermination of an entire people is extraordinary.”