NAIROBI (Reuters) - A Kenyan court on Thursday sentenced a former senior police officer to death for killing a detainee in his custody, one of the harshest punishments over widespread police brutality in the East African country.

FILE PHOTO: Nahashon Mutua, a former senior Kenyan police officer, is handcuffed in the dock at his trial in Nairobi, December 13, 2018. REUTERS/Njeri Mwangi/File Photo

Activists have long accused Kenyan police of using excessive force with little risk of being charged or convicted. A police oversight authority set up in 2011 ended virtual police impunity and fostered prosecutions for abuses.

Nahashon Mutua, a former senior police officer, was convicted on Dec. 13 of the murder of Martin Koome, who was found dead in a cell at a Nairobi police station where Mutua was in charge back in 2013.

“The evidence against Nahashon Mutua was overwhelming. The deceased suffered a lot of pain when he was assaulted by the officers,” High Court Judge Stella Mutuku said in her brief ruling. “This court has no other option but to sentence (him) to death since he is the one who committed the crime.”

Other officers in the station were not investigated by the IPOA in the Koome case.

Mutua has 14 days to appeal against the conviction.

Kenya’s Independent Police Oversight Authority (IPOA), established in 2011 after police killed hundreds of Kenyans during post-election unrest in 2007, can investigate police on its own initiative or after receiving a public complaint.

“This milestone decision (on Mutua) reiterates IPOA’s commitment to professionalise the National Police Service through holding to account culpable officers and exonerating those who are falsely accused,” IPOA said in a statement.

Death sentences are not unusual in Kenya but they are generally commuted to life imprisonment. No executions have been carried out since 1987.

Two other policemen were sentenced to death by the High Court last November for murdering a fellow officer and two civilians in a Nairobi bar in 2014.

Separately, an inquest court in the western city of Kisumu said on Thursday that 36 police officers should be held liable for the 2017 death of a six-month old baby, and called for criminal proceedings to begin.

The baby’s parents said the infant was teargassed and clubbed by police who invaded their home in Kisumu hunting for protesters after a disputed presidential election in August.