The mother of teenager Sylvester Muigai Ndung'u found his body in a mortuary in the central Kenyan town of Nanyuki two days after he went missing.

The 17-year-old was killed on Tuesday in clashes between police and demonstrators during a protest over a US plan to build an Ebola quarantine centre at a nearby military base.

Lucy Kagure had been searching for her son in hospitals and police stations and eventually discovered his body at the mortuary, where he was listed as an unidentified male.

"When I found him, half of his head had been split open. His clothes were soaked in blood," she told the BBC.

Witnesses said Muigai had been shot in the head, but a local police commander, Daniel Kitavi, told the BBC that the authorities were still waiting for a post-mortem to determine the cause of death.

Family members say police officers suggested he may have been killed by a tear-gas canister rather than a bullet.

Kagure said her son had left home on Tuesday to collect his school uniform from his aunt when he got caught up in the unrest.

"The police used too much force," she said through tears. "Are they not parents too?

"I have struggled to raise that boy as a single mother, earning just 300 [Kenya] shillings ($2.30; £1.70) a day doing casual work," she said.

"I brought him up from nursery school to form three, and then they just killed him."

His family described the teenager as a well-behaved boy who was always helping out at home.

A leader in the local church said he had ambitions of becoming a priest.

Muigai is the third person to have died amid protests against the planned 50-bed quarantine centre.

The isolation unit at the Laikipia Air Base is intended for US citizens affected by the current Ebola outbreak in the Democratic Republic of Congo.

The plan has sparked public concern in Kenya about cross-border infection risks and the lack of transparency from the government about the treatment centre.

Last month, the High Court said the opening of the facility should be halted after a rights group opened a case alleging it posed "grave and imminent risks" to public health.

Satellite imagery seen by the BBC show that construction has continued at the airbase despite the court halting it.

The US official last week said the administration was aware of the court case but "optimistic we can resolve objections".

Kenya's President William Ruto defended the plan, saying he had received a request from the US to establish the centre and a refusal would be "inhuman".

He called on Kenyans not to politicise a matter "so serious" as Ebola, asking politicians to avoid "reckless" talk about it.

On Tuesday, demonstrators had planned a peaceful march to deliver a petition calling for the facility to be relocated. But clashes broke out after police blocked access to the site.

Police used tear gas and water cannon to disperse crowds, while protesters erected roadblocks and lit bonfires across parts of the town.

The Kenya Human Rights Commission, a non-governmental organisation, has accused police of using excessive force, including live ammunition and arbitrary arrests during the demonstrations. The authorities have not responded to those allegations.

But a mourning mother now wants answers.

"I want justice for my boy," she said.