Kenyan Vice-President William Ruto was due to fly to The Hague from Nairobi on Monday, a day before the start of his crimes against humanity trial at the International Criminal Court.
Ruto, 46, is charged with masterminding deadly post-election violence five years ago. He is the most senior politician to date to face ICC judges, and his trial starts just days after Kenyan lawmakers voted to abandon the court in a world first.
Ruto shook hands with supporters in Nairobi and waved smiling to a small crowd at the airport as he left, but made no comment.
Kenya's 2007-2008 post-election unrest left at least 1,100 dead and more than 600,000 homeless.
Fellow accused Joshua arap Sang, a radio boss accused of inciting and helping coordinate attacks during the violence, is already in The Hague, after flying there over the weekend.
Both will plead not guilty to all charges.
On Sunday, Ruto prayed in church alongside President Uhuru Kenyatta, who himself stands accused of organising a campaign of murder, rape, persecution and deportation during the post-election unrest. Kenyatta's own ICC trial begins on 12 November.
However, Kenyatta on Sunday said that he will not allow both leaders to be out of the country at the same time.
"We will work with (the) ICC, and we have always promised to do this," Kenyatta told supporters at a rally. "But it must understand that Kenya has a constitution, and Ruto and myself won't be away at the same time."
Judges in the two cases will have to decide on timings later on, after Kenyatta's trial begins, but the chief judge in Ruto's case, Chile Eboe-Osuji, said he would prefer for the cases not to run concurrently.
"The chamber's preference would be sitting in alternating periods of a judicial calendar," he told journalists.
"That vision entails a minimum block of four weeks of the judicial calendar exclusively devoted to one case," he said, meaning the cases would be heard four weeks at a time.
Kenya's 2007 elections were marred by allegations of vote rigging, but what began as political riots quickly spiralled into a wave of ethnic killings and reprisal attacks, the worst violence in the country since independence in 1963.
Ruto's lawyer on Monday sought to dismiss widespread allegations of witness intimidation as a prosecution "smoke screen" to hide a weak case against his client.
Alleged witness intimidation is an extremely sensitive issue in the trials and is frequently evoked by ICC chief prosecutor Fatou Bensouda and rights groups, with several witnesses already having pulled out.
"I do not want anybody to be seduced or brought into the nonsense that has been bandied about that the witnesses of the prosecution case are somehow (the target) of intimidation or bribery or some kind of underhand conduct by the defence," Ruto's lawyer Karim Khan told reporters in The Hague.
"Let's blow away the smoke screen that is being raised to hide what we say are the deficiencies, unfortunately, of the office of the prosecutor."
Bensouda told the same press conference that she was "certain" that witnesses were being targeted by intimidation and other "interference."
She has previously accused the Kenyan government of obstructing the case, adding that witness intimidation had reached "unprecedented" levels.
Human Rights Watch on Monday called the case the "first real effort" to look at responsiblity for the killings.
"For decades those who have turned Kenya's elections into bloodbaths have gotten away with murder," HRW Africa director Daniel Bekele said in a statement.
"This ICC trial tackles an impunity crisis in the country and offers a chance for justice denied to Kenyans by their own government."
But there is also concern in Kenya that the trials could re-open old wounds and undo reconciliation efforts by communities who once fought each other in deadly battles.
Law Society of Kenya chairman Eric Mutua on Monday warned that "heavy political statements and debates on the ICC process may tear the country apart," in a statement urging "leaders and the public to exercise caution as justice takes its course."