New York-based journalist Jonathan Silvers has spent the past year investigating fugitive Nazi war criminals for his forthcoming documentary "Elusive Justice". Silvers and Brian Barron collaborated on a Newsnight report, which centres on a 92-year old grandfather who may soon become the oldest war criminal deported from the United States.
At first glance Vladas Zajanckauskas seems the picture of a contented grandfather; an American patriarch in his 90s, proud of his successful immigrant family in New England.
He likes to relax by drawing, especially images of playful innocence. But to some who know the details of his earlier life as a young soldier in Europe, his name conjures up demons.
Eli Rosenbaum, the director of the US Justice Department's Office of Special Investigations (OSI), says there is clear, documentary evidence that Vladas Zajanckauskas was part of Nazi Germany's extermination squads, and was "a thrice-promoted, non-commissioned officer (NCO) at a school of mass murder".
Mr Zajanckauskas denies he was part of the extermination squads or - another specific charge - that he participated in the destruction of the 1943 Warsaw Ghetto uprising.
It is nearly 70 years since Hitler ordered the invasion of the Soviet Union, after occupying Western Europe. Behind his armies came the SS with extermination units known as the Einsatzgruppen.
Ben Ferencz, the last surviving American prosecutor at the Nuremberg War Crimes trials says these were the orders given to the Einsatzgruppen: "You will kill every Jewish man, woman and child you can lay your hands on. You do the same for the gypsies. You do the same for communist officials or anyone you suspect may pose a present or future threat to the Third Reich. You eliminate them root and branch."
The enormous scale of the extermination programme meant that the SS needed manpower but a growing number of German soldiers were being sent to the Eastern front where Soviet resistance was growing.
Around 13,000 Warsaw Ghetto Jews died resisting deportation
So the SS recruited non-Germans from Baltic states like Lithuania, where there were grievances against the Soviet Union.
Vladas Zajanckauskas was a 21-year-old Lithuanian soldier who had been press-ganged into the Soviet army and then captured as a prisoner of war by the Germans. He claims that at first he refused to become a prison guard for them and so was brutalised.
"They took us, told us to take our pants off and put our heads in barrels and beat us with whips. And the whips were made of flexible wire and leather. They killed my friend right there," he said.
Under that sort of coercion, he signed up for the SS training camp at Trawniki in Poland and insists he was only assigned to the kitchen and bar to serve German soldiers. But the OSI says he was a senior NCO who could leave the camp if he wanted and was given a weapon and permission to marry.
A lifetime later he has a selective memory about what happened. At a US Federal Court where the OSI successfully demanded he forfeit his American citizenship, he damaged his credibility when asked about a massacre of Jews at Trawniki.
Mr Zajanckauskas was not accused of taking part, but given his privileges at the camp, the judge found it incredible that he was ignorant of what was happening.
And the court did believe evidence that suggested he was involved in the liquidation of the Warsaw ghetto.
His lawyer, Tom Butters, said later: "Sometime in late 1943 or early 1944 something like 1,000 prisoners from the camp were brought into the courtyard outside of Trawniki and were simply slaughtered by the Germans and the bodies were burned for several days. Vladas Zajanckauskas denied at the trial he knew anything about that."
What proved to be his final undoing was a captured SS duty roster - extracted from Russian state archives after the collapse of the Soviet Union - which had the name of Vladas Zajanckauskas among over 300 SS men from Trawniki assigned to one of the most notorious Nazi crimes of World War Two.
OSI director Eli Rosenabaum describes what happened.
"Vladas Zajanckauskas and other Trawniki men were sent to Warsaw on 17 April, 1943, to see to it that the Jews of Warsaw, tens of thousands of people, were killed. It was a murder mission. That's what he did. He took part in the annihilation of the Jews of Warsaw."
The uprising was triggered by the Nazi plan to send 50,000 people to the extermination camp at Treblinka.
In the end the Jewish fighters, lacking adequate weapons and supplies, were overwhelmed - 13,000 died in the ghetto, many burned alive. Tens of thousands more were murdered later at Treblinka. The German commander of the Warsaw operation was tried and executed as a war criminal after the Nazi surrender in 1945.
Vladas Zajanckauskas is adamant he knew nothing about it.
"I never…they never send me to the Warsaw Ghetto," he says. "I never was over there. I was in Trawniki, yes. I will admit that. But I'll never admit until I die that I was in Warsaw."
Mr Zajanckauskas draws to pass time - he says he is waiting to die
Eli Rosenbaum says the common reaction among most of the suspects and defendants he has dealt with is denial. "They all deny something… some deny more than others."
Overall the OSI has deported about 100 suspected war criminals - under the US constitution they can only be stripped of their citizenship and expelled - and there are still 20 individuals under investigation.
Mr Zajanckauskas admits he lied to get into America after the war and did not disclose his SS background.
The fact is that increasingly the hunt is focused on geriatrics. Vlad Zajanckauskas is over 90.
If he loses his final appeals and is deported he will be the oldest suspected war criminal to be dealt with in that way.
Mr Rosenbaum admits: "Time is our biggest enemy in these cases. We have to literally race the grim reaper. Sometimes he wins. The principal strategy of most defence lawyers is delay… so that their clients can die in freedom in the US."
As if to confirm that, Vladas Zajanckauskas starts weeping during our interview and says: "I hope they wouldn't deport me. Last my days…and I already bought a grave for myself in cemetery, with stone, with everything. My name. My wife's name.
"It's not too many days left to die."