His neighbours know him only as Celestin, a scrupulously polite man who emerges from his home to attend church, or tend his garden in the street of neat bungalows on the Essex coast, where he has lived since 2000. To the government of Rwanda, and to his alleged victims, he is Mayor Celestin Ugirashebuja, a man accused of directing and inciting the slaughter of hundreds of ethnic Tutsis - allegations he denies - during the 1994 genocide, during which at least 800,000 people were killed.
Five months ago, Rwanda's prosecutor general, in charge of tracking down 100 suspected "genocidaires" living abroad, issued an arrest warrant to the Home Office and Scotland Yard via Interpol, asking for Mr Ugirashebuja to be arrested.
It is the British Government's policy that no genocide suspect will be allowed to live in the UK without facing trial here, or extradition.
But when The Independent tracked down Mr Ugirashebuja to the seaside town of Walton on the Naze this week, he had yet to receive a visit from the police.
To date, he has not been arrested or interviewed about the allegations against him. The 55-year-old former mayor of the rural commune of Kigoma, close to Kigali, the Rwandan capital, is one of at least three suspects known to be living in the UK whose names appear on a list of the 100 most-wanted genocide suspects issued by Rwanda. Mr Ugirashebuja stands at number 93 on the "Category One" wanted list.
Charles Munyaneza, 48, another mayor accused of organising mass killings, is number 54 on the list. He lives in Bedford, has not been arrested or interviewed, and has been granted indefinite leave to remain in the UK.
A third man, who cannot be named, is known to live in North-west England after apparently being granted permission to stay in Britain on the basis of false evidence about his identity.
Senior backbench MPs, led by the former Cabinet minister Clare Short, have written to the Home Secretary John Reid demanding the removal of any "legal obstacles" preventing the prosecution of the suspects.
Human rights activists point out that the presence of the men in Britain is all the more shocking given the allegations against them.
According to the summary indictment issued against him by the Rwandan authorities, and seen by the Home Office and the Yard, Mr Ugirashebuja, a member of the Hutu majority in Rwanda, chaired meetings after the genocide began in April 1994 in which he exhorted the killing of Tutsis in his region.
"He held meetings in different sectors, during which he sensitised Hutus to kill Tutsis. Some of the meetings he held prompted massacres of Tutsis at a very large scale," the indictment says. It cites one meeting at Muyange primary school: "During that meeting, Ugirashebuja told people to identify and get rid of the enemy. He told them that if they didn't do it, the enemy would push them in Lake Kivu. He urged Hutus to kill Tutsis and to destroy their property. After that meeting, massacres escalated."
At another gathering in a village called Progress, the former mayor is accused of telling a meeting of villagers that peace had been restored and all Tutsis should come home. The indictment adds: "All the Tutsis who came back were killed."
The document claims Ugirashebuja had a "direct hand" in five separate massacres and individual killings. When asked at his home about the allegations, Ugirashebuja denied his involvement and said they were part of plot against him. He said: "It is all lies. We are people of God. They [the Rwandan government] want to kill all Hutus in England. It is all lies against me."
The Independent has learned the men were the subject of a preliminary inquiry in 2003 by a specialist Yard war crimes unit after their details were passed on by Home Office immigration officials, but no action was taken against them.
It is understood that Mr Ugirashebuja and the two other men have not been arrested because Britain's war crimes legislation, while it makes it possible to prosecute Nazi suspects, currently does not extend to the Rwandan genocide. There is also no extradition agreement between Britain and Rwanda, although a Government minister has signalled the possibility of "one-off" extraditions.
In a sign of the growing frustration at the ability of the suspects to live in Britain with impunity, the Rwandan ambassador to the UK, Claver Gatete, publicly criticised the Government for its lack of response.
"One would expect the British Government, given its very clear stance on genocide suspects, to take action in the light an international arrest warrant," he said.
"We have made it clear to the Government that we are prepared to offer all the commitments required to secure extradition, including the suspension of the death penalty, or a trial in the UK. But we still await a response."
The Home Office declined to comment on individual cases. But a spokesman said: "We are committed to ensuring that no war crime suspect should enjoy impunity in this country."Reuse content