A Kenyan police officer has appeared before a Nairobi court charged with the murder of 23-year-old Carilton Maina, a former Leeds University student, who was shot dead in December 2018.

The charging of police constable Emmanuel Ambunya Oyombe marks a significant milestone in the Kenyan government’s commitment to tackling its issue with questionable police shootings, and to speeding up its justice process in bringing those accused to trial.

The Milimani high court hearing on Thursday was held outdoors, in response to the coronavirus pandemic, the first time this has happened in Kenya since the 1950s state of emergency.

Oyombe, who remains a serving police office, pleaded not guilty to murder. A trial date has not yet been set.

He was arrested last week, according to an announcement made on social media by Kenya’s director of criminal investigations. The director said the officer would be charged with the murder of Maina, who “succumbed to gunshot wounds inflicted on him by the said officer”.

Irungu Houghton, Amnesty International’s director in Kenya, who has been lobbying the government to do more to stop such incidents, said on Thursday he had taken a keen interest in the case and welcomed the investigation.

Maina’s mother, Josephine Wangare, was in court, supported by a legal team from Amnesty. She said seeing someone brought to court to face trial had restored her faith in justice.

“I am grateful,” she said. “The death of my son Carilton has been very painful for us and his friends. He was greatly loved. After a year with no one prosecuted for his death I had begun to despair.”

Maina was raised in Kibera, Africa’s largest slum. A straight-A student, he showed exceptional talent, which eventually earned him a scholarship to Leeds University in the UK. He had returned to Kibera over the Christmas holidays and was walking home on 22 December from watching a televised football match with friends when they met two police officers.

It is said that there was an exchange of words and Maina ran from the officers. At Laini Saba, a short instance from the home where he lived with his grandmother, he was hit by four bullets to his body and head.

Last year the Guardian interviewed Josephine Wangare about the killing, which had sparked outrage in the local community. Students took to the streets in protest with placards demanding “Justice for Maina”.

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The court case comes against a background of Kenya’s questionably high police-related deaths – referred to as “extrajudicial killings” by communities and local news reports – often shootings after street interventions or stops.

In an attempt to bridge the gap between themselves and people in Kibera, the Kenyan police have been carrying out a community engagement programme aimed at building trust and rooting out those who prey on the vulnerable. Gang rape, murder and robbery are all too common occurrences in the slums. Officers are targets for criminals and gangs in slums such as Kiberathat are dangerous and difficult to patrol. Several have been killed over the past few years.

Kenya’s government claims to be making an effort to weed out the rogue officers among its 60,000-strong police force. As of March 2018, the country’s Independent Policing Oversight Authority was monitoring 9,878 outstanding complaints against police, of which 5,085 were earmarked for detailed investigation.

• This article was amended on 29 April 2020 to remove an erroneous reference to the city of Kisumu as a “slum”.