The High Court on Thursday found former Ruaraka OCS Nahashon Mutua guilty of killing an inmate six years ago.
The inmate, Martin Koome is said to have been tortured to death by Mr Mutua.
“The Prosecution has proved beyond reasonable doubt that the police caused the deceased suffering while in cells which caused his death,” said Lady Justice Stella Mutuku.
In December 13, 2018, the Court ruled that the element of malice aforethought had been proven.
Nahashon had denied the charges and noted that he was on duty when he received information that the inmate had been injured.
According to the Prosecution however, the OCS hit the inmate several times with a rod and forcefully immersed his head in a drum of water for about 30 minutes.
He then locked him up in the cell, even though he had sustained serious injuries.
Koome, 36, died on December 20, 2013 while undergoing treatment at the Kenyatta National Hospital.