A Kenyan policeman is to be charged with murder after being filmed shooting at two men who were later found dead during election protests, police say.
The shooting in the western city of Kisumu shocked the country and led to an official enquiry.
Former UN chief Kofi Annan, who is mediating peace talks, says it is too dangerous to hold new polls for a year.
An estimated 1,000 people have been killed and 300,000 others fled their homes during the clashes.
Meanwhile, the talks between the government and opposition aimed at ending five weeks of unrest are on the brink of collapse, says the BBC's Noel Mwakugu in Nairobi.
He says the two sides could not agree on a proposal to share power while fresh presidential elections were organised.
The United States has put a travel ban on 10 MPs from both sides for allegedly being involved in the violence since dispute elections.
Kenya's KTN television, which broadcast the footage of the protesters allegedly being killed, reports that Constable Edward Kirui has been arrested and transferred to Nairobi, where he is to appear in court.
He was seen firing his gun as protesters taunted police during protests at alleged election fraud in the opposition stronghold of Kisumu on 16 January.
He then went over to one of them as he lay on the ground and kicked him in the back.
George William Onyango and Ishmael Chacha were later found dead with bullet wounds.
The opposition has accused the police of having a shoot-to-kill policy.
The UN humanitarian affairs coordinator Louise Arbour has sent a fact-finding mission to investigate human rights violations during the violence.
The US envoy in Kenya Michael Ranneberger said those affected by the travel ban had been notified by his office and the move would also affect their immediate family members.
Government spokesman Alfred Mutua welcomed the move and urged the US to name those affected to avoid speculation.
"This is a commendable move and it exhibits the American government's strong stand on crimes against humanity and genocide," he said in a statement.
Kofi Annan (l) has brought the rivals together but they can't agree
The opposition Orange Democratic Movement is yet to respond.
Both sides have accused their rivals of ethnic cleansing after attacks on members of ethnic groups seen as backing either President Mwai Kibaki or ODM leader Raila Odinga.
Mr Kibaki was declared the winner but Mr Odinga says he was cheated of victory.
The talks led by Mr Annan were adjourned on Wednesday amid sharp disagreements.
"I would be totally opposed to a re-election in this climate. There's lots of insecurity around parts of the country," the former UN secretary general said.
The government team insisted that the dispute be resolved through legal means or constitutional reforms.
Both sides were however in agreement that re-tallying or a recount of the presidential votes should not be done.
The ODM has questioned the independence of the judiciary and the integrity of the Electoral Commission of Kenya (ECK).
Mr Annan says tough issues have returned to haunt the talks but both groups have found common ground on the need to disband and reconstitute the ECK.
On Wednesday, the UN Security Council called on Kenya's political leaders to solve the crisis there through "dialogue, negotiation and compromise".
In its first official response to the unrest sparked by December's disputed election, the council expressed concern at the "dire humanitarian situation".
Foreign ministers from Djibouti, Ethiopia, Sudan, Uganda and Somalia have arrived in Nairobi for a meeting of the East African regional group, Igad, on Thursday to discuss the crisis.