According to Nairobi Police Boss Joseph ole Tito, the officer was off duty when he was confronted by his killers who wanted to rob him of his money and other valuables.
He said the officer resisted, prompting the stabbing.
“This incident happened soon after he alighted from the matatu he was travelling in and he was stabbed as he tried to resist (being robbed).”
He stated that the officer died on the spot as his attackers escaped on foot.
Elsewhere, police are investigating an incident where a man was found dead after he inhaled carbon monoxide from a jiko he had lit, in Kariobangi area of Nairobi Tuesday night.
According to officers, the man had been alone in his house when he was found dead.
Police said his wife was away at the time of the incident.
And in Kabete, the body of a lecturer was found in his house after a suspected sudden death.