Lawyer Paul Gicheru, who was a witness at the International Criminal Court (ICC), was found dead in his Karen residence, Nairobi.
According to preliminary investigation, he allegedly collapsed and died.
The date for an autopsy examination is yet to be set.
Gicheru surrendered to Hague authorities in November 2020 after evading a warrant of arrest issued back in March 2015.
The lawyer was accused of bribing and intimidating witnesses in the failed ICC case against President William Ruto.
In 2016, ICC judges ruled that Ruto had no case to answer, noting that the case had been hampered by political interference and threats against witnesses.
The case has since been terminated about a year after a similar suit against former President Uhuru Kenyatta was discontinued in March 2015.
In his submissions, Gicheru asked the court to dismiss the case against him, while the prosecution has called for a guilty verdict on all 8 counts that the lawyer faces.
However, the prosecution argued that arguments by the defence had no merit and should not have a bearing on the outcome of the case, calling on the chamber to find Gicheru guilty.
Other Kenyans who faced charges of crimes against humanity at the ICC alongside Kenyatta and Ruto is Sang, Kosgei, Francis Muthaura and police chief Mohammed Ali.