Paul Gicheru was accused of tampering with witnesses in favor of President William Ruto, whose trial at The Hague collapsed in 2016. The cause of death is not yet known.NAIROBI, Kenya — A Kenyan lawyer on trial at the International Criminal Court on charges of witness tampering in a case linked to President William Ruto was found dead at his home in a suburb of the capital, Nairobi, his family and the police said on Tuesday.The lawyer, Paul Gicheru, had been awaiting a verdict in the trial, which took place in The Hague from February to June. Prosecutors accused him of bribing and intimidating witnesses to prevent them from testifying against Mr. Ruto over his role in post-election violence in Kenya in 2007 and 2008.Mr. Ruto, who announced his new cabinet on Tuesday, was sworn in as president on Sept. 13 after winning last month’s hard-fought election by a narrow margin.Michael G. Karnavas, Mr. Gicheru’s lawyer, confirmed his death, which was received with shock by many in Kenya — the latest twist in a decade-long legal journey at the International Criminal Court, punctuated by collapsed trials, disappearing witnesses and accusations of meddling, that has drawn in Kenya’s leaders and framed its politics.Kenyan news reports, citing the police, said that Mr. Gicheru went to sleep on Monday after a meal at his home in Karen, a wealthy Nairobi suburb, and was found dead later that night. His son was taken to a hospital and complained of stomach pains after eating the same meal.Mr. Karnavas said that he suspected foul play and called on the Kenyan authorities and the International Criminal Court to open a full investigation into the death. “It’s somewhat odd that after the election in Kenya, and before the court issues its judgment, there is this incident,” he said, speaking by phone. “This warrants the I.C.C. stepping up to the plate.”But in comments to reporters in Kenya, John Khaminwa, a lawyer for the Gicheru family in Kenya, downplayed suggestions of poisoning, and said the family was waiting for an autopsy to be completed and for the police to issue its preliminary report.Mr. Gicheru caused a sensation in Kenya in late 2020 when he flew to Amsterdam to present himself to the International Criminal Court, after years of refusing to stand trial and resisting the court’s efforts to have him extradited to The Hague.When the trial started this year, Mr. Gicheru pleaded not guilty and declined to testify. He returned to Kenya when the trial ended in June to await the verdict. A spokesman for the International Criminal Court said in an email that under the court’s guidelines, a verdict should be delivered within 10 months.President William Ruto of Kenya at the U.N. General Assembly last week. He was sworn in this month after winning a hard-fought election in August by a narrow margin.Dave Sanders for The New York TimesThe Kenya Human Rights Commission called the news of his death “shocking,” and urged the authorities to mount a swift investigation. In a statement, the Law Society of Kenya reiterated that call, noting that “several witnesses in the I.C.C. cases have either disappeared or died,” and wished a speedy recovery to Mr. Gicheru’s hospitalized son.Mr. Gicheru’s trial stemmed from a series of high-profile prosecutions that implicated some of Kenya’s most prominent politicians in a wave of violence after the disputed 2007 elections that killed at least 1,200 people and forced another 600,000 to flee their homes.In 2011, the International Criminal Court indicted Mr. Ruto for crimes against humanity over accusations that he orchestrated violence in his home area, the Rift Valley, distributing weapons and issuing kill lists of opposition supporters from rival ethnic groups.Uhuru Kenyatta, then a political rival of Mr. Ruto, was also indicted on similar charges.By 2016, the cases against both men collapsed after key witnesses recanted their testimony and the Kenyan government stopped cooperating with the court. By then, Mr. Ruto and Mr. Kenyatta had resolved their political differences to unite as a formidable force. Together they won the 2013 election, with Mr. Kenyatta as president and Mr. Ruto as his deputy, and were re-elected in 2017.Not only did the I.C.C. charges unite the two leaders, but it also provided them with a powerful electoral argument. After becoming president in 2013, Mr. Kenyatta denounced the court as a “toy of declining imperial powers.”But in dismissing the charge against Mr. Ruto, the court did not declare him innocent, leaving open the possibility that he could face a new trial. And it had already, in 2015, indicted Mr. Gicheru, a provincial lawyer from the same area as Mr. Ruto, on accusations that he ran a witness tampering scheme responsible for scuppering the trial.During the trial that started in February, prosecutors said that Mr. Gicheru had intimidated or offered bribes of up to $41,600 to witnesses who withdrew their testimony against Mr. Ruto and Joshua Sang, a radio journalist accused of stoking political violence in the Rift Valley after the 2007 vote.Prosecutors told the court that Mr. Gicheru’s actions, from 2013 to 2015, had caused four “vital” witnesses to recant their testimony. Eight people testified against him, including witnesses who said that they been threatened and that they feared for their lives.The prosecutor of the International Criminal Court, Karim Khan, recused himself from the Gicheru case because he had represented Mr. Ruto as a defense lawyer during the trial that collapsed in 2016.Protesters and the police in Eldoret, Kenya, in 2008. Mr. Gicheru had been accused of intimidating witnesses to prevent them from testifying against Mr. Ruto over his role in post-election violence in Kenya in 2007 and 2008.Ben Curtis/Associated PressAfter Mr. Ruto’s case collapsed, the International Criminal Court prosecutions receded from prominence in Kenya. Mr. Gicheru, by then a senior Kenya government official, successfully opposed efforts by the court to have him extradited to The Hague.But the affair returned to prominence in November 2020 when Mr. Gicheru voluntarily flew to The Hague with his wife and presented himself for trial at The Hague.The unexpected move by Mr. Gicheru stoked widespread speculation inside Kenya that it was linked to the crumbling relationship between Mr. Kenyatta and Mr. Ruto. Two years earlier, Mr. Kenyatta had signed a political pact with Raila Odinga, a veteran opposition leader expected to contest the 2022 election, that his deputy, Mr. Ruto, saw as a betrayal.When Mr. Gicheru presented himself for trial in 2020, reports in Kenyan news media speculated that he had been pressured or inducted to present himself for trial as part of an effort to resurrect the I.C.C. case against Mr. Ruto.His lawyer, Mr. Karnavas, said Mr. Gicheru’s motivation was simply to clear his name. “It was a sword of Damocles,” Mr. Karnavas said.During the hearings early this year, no evidence emerged that directly linked the witness tampering scheme to Mr. Ruto, and the issue hardly figured in the bitterly fought election campaign that ended in August, with Mr. Ruto’s narrow victory over Mr. Odinga.Mr. Karnavas said the prosecution’s case was weak and, had Mr. Gicheru lived to hear the verdict, he was confident he would have been acquitted.“Here’s someone who came voluntarily to clear his name, knowing the consequences,” he said. “Even if there’s no foul play, there needs to be an investigation.” More