By Malcolm Haslett
BBC Eurasia analyst
One of the world leaders attending the Holocaust memorial ceremonies at Auschwitz on Thursday had a particular personal link with the camp.
Mr Yushchenko lit a candle at the Auschwitz ceremony in Poland
The father of new Ukrainian president Viktor Yushchenko was a prisoner there.
Mr Yushchenko has put a heavy emphasis on his father's internment in Auschwitz, and for obvious reasons.
In the past, his opponents have depicted him not just as a right-wing nationalist working for the US, but as a Nazi, plain and simple.
During the recent election campaign billboards in the eastern city of Donetsk portrayed Mr Yushchenko in Nazi uniform giving a Nazi salute.
Opponents in Ukraine and Russia have also played on his wife's US citizenship and her alleged connections with American right-wing circles.
In 2001, the Russian television presenter Mikhail Leontiev, known for his controversial pro-Kremlin sympathies, accused Mrs Kateryna Yushchenko of being a "CIA agent" sent to Ukraine to bring her husband to power.
Mrs Yushchenko won a libel case in a Ukrainian court against Mr Leontiev and his "Odnako" [However] programme.
But that did not end the accusations, which reached a new high point in the run-up to the election.
Critics attacked Kateryna Yushchenko's US links
To bolster their accusations, Mr Yushchenko's detractors pointed to the undeniable fact that right-wing nationalist groups in the Ukraine, such as UNA-UNSO (Ukrainian National Association), clearly supported Mr Yushchenko rather than the Russian-backed candidate Viktor Yanukovych.
Mr Yushchenko has tried all along to distance himself from the extreme right, and at one point told UNA-UNSO to go and campaign for his opponent instead.
The chance to advertise his father's imprisonment and suffering in Nazi concentration camps has now given his case a strong fillip.
But his opponents have also been trying to imply that his wife's family has shady secrets. There have been suggestions that hers parents, who emigrated to the US from Germany in the 1950s, had either collaborated with the Nazis or at the very least shown disloyalty to their homeland by not returning home after the war.
Mrs Yushchenko, however, has pointed out that many thousands of Ukrainians were taken to Germany during the war as slave labour, and those who returned to Stalin's USSR after the war often ended up being sent back to work camps - these ones run by the Soviets.
In his speech at Auschwitz, Mr Yushchenko pledged to work for the elimination in Ukraine of "anti-Semitism, xenophobia and hatred among people".
That will not stop the new president's opponents from continuing their attacks on his integrity.
Yet in the eyes of international opinion, the episode of Mr Yushchenko's poisoning last October, and the admitted fraud in the first count, give the new Ukrainian president a huge advantage over his critics in terms of credibility.