The Independent Policing Oversight Authority has launched investigations into the killing of a Leeds University student in Kibera on Friday night.
Carilton David Maina, 23, was shot dead by police officers in Laini Saba.
Police say he was in a group of muggers but witnesses dispute that account.
“Ipoa has learnt of the unfortunate incident in which members of the National Police Service killed Mr Carilton David Maina,” the authority’s communication head Dennis Oketch said in a statement.
He added that Ipoa would be independent, impartial and fair during the investigations.
The shooting cut short the life of the former Maseno School student who scored straight As in the Kenya Certificate of Secondary Education examination in 2013.
The engineering student and his friends had gone to watch a football match when they were confronted by police officers.
Maina’s friends told journalists that the officers appeared more interested in killing than arresting anyone.
Kilimani police boss Michael Muchiri told Nairobi News that locals alerted police about muggers harassing them.
“We received a call from the public. Police acted and shot one,” Mr Muchiri said.
Amnesty International said the killing dents the narrative police often tell about shootings.
“It shatters the myth that only violent criminals are killed lawfully. The shooting has the hallmark of extra-judicial killing and must be investigated,” Amnesty executive director in Kenya Houghton Irungu, said in a statement.