Paul Gicheru had been accused by ICC prosecutors of running an "egregious and damaging" witness tampering scheme that made it impossible to pursue allegations against President William Ruto.
Kenyan police are investigating the death of a lawyer who was on trial for allegedly bribing and intimidating witnesses in the failed International Criminal Court case against President William Ruto, an officer has said.
"The information we have from the family is that he had a meal and went to sleep and never woke. He was found dead in the house late Monday evening," a senior police official told AFP news agency on Tuesday on condition of anonymity.
"An investigation is under way because we do not know the cause of death yet," he said, adding that Gicheru's son had been taken to hospital after complaining of stomach pains following their meal together.
Paul Gicheru had been accused by ICC prosecutors of running an "egregious and damaging" witness tampering scheme that made it impossible to pursue allegations against Ruto over post-election violence in Kenya in 2007-2008.
His trial opened in February this year, with prosecutors alleging that Gicheru paid bribes of up to one million Kenyan shillings ($8,300) and threatened the safety of ICC witnesses, one of them at gunpoint.
Gicheru had denied the allegations throughout, pleading not guilty at The Hague-based court, which is the world's only permanent war crimes tribunal.
The Kenya Human Rights Commission urged the authorities to "conduct swift and conclusive investigations" into the lawyer's death.
"While the full details surrounding this death are still emerging, we remain concerned with the shocking news of the untimely death of Kenyan lawyer Paul Gicheru," the KHRC said on Twitter.
While the full details surrounding this death are still emerging, we remain concerned with the shocking news of the untimely death of Kenyan lawyer Paul Gicheru who was facing charges of witness interference at the International Criminal Court. https://t.co/KcGRAFtwJ6— KHRC (@thekhrc) September 26, 2022
The disputed 2007 vote in Kenya was followed by the worst post-electoral violence in the country's history and left 1,100 people dead.
Gicheru had "managed and coordinated a scheme to identify, locate and corruptly influence" witnesses throughout the ICC trial of Ruto and co-defendant Joshua Sang, which collapsed in 2016, ICC deputy prosecutor James Stewart had said.
Four "vital" prosecution witnesses had recanted their testimony as a result of Gicheru's actions.
Another two witnesses reported him to the ICC, Stewart said.
Prosecutors noted that of the individuals "caught up in the witness tampering scheme", one witness had died and another had disappeared — although there were no allegations that Gicheru had been directly linked to their fate.
The ICC had also launched a case against former president Uhuru Kenyatta over the post-electoral violence. That too collapsed in 2014.
Ruto, who served as Kenyatta's deputy for nine years, was elected president in a bitterly-fought but largely peaceful vote held last month.