Family spokesman Saitoti ole Maika had earlier said the procedure was conducted in the presence of two family doctors and a family member.
Also at Lee Funeral Home were Directorate of Criminal Investigation officers, including the Nairobi County DCI boss Nicholas Kamwende and Kilimani DCIO Phyllis Kanina.
The bereaved family appealed to Kenyans to be patient until investigations were complete and made public.
The postmortem was done a day after the CS’s widow Hellen Nkaissery, who was admitted at the Nairobi Hospital since her husband’s death on Saturday morning, was discharged.
“We are also glad to announce that Mrs Nkaissery, who had been hospitalised following the death of her husband, is now out of hospital,” said Mr Maika.
Sources told the Nation that the family had postponed the autopsy to await the arrival of the CS’s sons from abroad.