Former Ruaraka OCS Nahashon Mutua has been sentenced to death after he was found guilty of killing a Miraa trader in 2013.
High court Judge Stella Mutuku on Thursday said the prosecution has proved its case beyond reasonable doubt.
She said Martin Koome received inhumane treatment and there is no doubt that Mutua caused his death.
Koome said there is little anyone can say or do to cushion the bereaved family against the pain caused by the death of their family member.
"Only acceptance and time will heal their pain. It is an irrefutable fact that the death of Koome has deprived his family a bread winner, a husband and a father. This fact has changed their lives forever," she said during the ruling.
Mutua has 14 days to appeal the ruling.
In a High Court ruling last year, Mutua was found guilty of killing Koome, an inmate at Ruaraka police station.
He tried to frame Kevin Odhiambo, another inmate at the station, for it. Koome was a miraa trader at Baba Dogo shopping centre in Ruaraka, Nairobi.
He had returned home drunk after the day’s work and is said to have “normal” domestic squabbles with his wife.
The prosecution showed the trial court how Mutua went to great lengths to obstruct justice, even offering an Sh1 million bribe to investigators besides trying to frame Odhiambo.
The case is the first high profile conviction of an officer accused of extrajudicial killing.