Pictures have emerged of Radovan Karadzic at a conference in January in his disguise as Dragan Dabic
Captured war crimes suspect Radovan Karadzic was living in Serbia's capital Belgrade and practising alternative medicine, Serb officials say.
He was sporting a long white beard and calling himself Dragan Dabic, said Serbian minister Rasim Ljajic.
The former Bosnian Serb leader was arrested on Monday near Belgrade after more than a decade on the run.
He has been indicted by the UN tribunal for war crimes and genocide relating to the war in Bosnia in the mid-1990s.
The UN says Mr Karadzic's forces killed up to 8,000 Bosniak men and boys from Srebrenica in July 1995 as part of a campaign to "terrorise and demoralise the Bosnian Muslim and Bosnian Croat population".
He has also been charged over the shelling of Sarajevo, and the use of 284 UN peacekeepers as human shields in May and June 1995.
Eleven counts of genocide, war crimes, crimes against humanity and other atrocities
Charged over shelling Sarajevo during the city's siege, in which some 12,000 civilians died
Allegedly organised the massacre of up to 8,000 Bosniak men and youths in Srebrenica
Targeted Bosniak and Croat political leaders, intellectuals and professionals
Unlawfully deported and transferred civilians because of national or religious identity
A judge has ordered Mr Karadzic's transfer to the UN war crimes court in The Hague.
The chief prosecutor in The Hague, Serge Brammertz, said the arrest made clear that no-one was beyond the law.
Mr Karadzic's lawyer, Sveta Vujacic, has said he will appeal against the ruling; he has three days to do so.
Groups of demonstrators have gathered in Belgrade to confront long lines of riot police, shouting, chanting and throwing missiles, says the BBC's world affairs editor John Simpson in the Serbian capital.
It looks as this may be the start of some violent demonstrations against the handover of Mr Karadzic, he adds.
Mr Ljajic, the Serbian minister for relations with The Hague tribunal, said Mr Karadzic had lived in a "very convincing" way, using false papers.
"He was involved with alternative medicine, earning his money from practising alternative medicine... he was working in a private practice," he told a news conference in Belgrade.
Serbia's war crimes prosecutor Vladimir Vukcevic said Mr Karadzic had "walked around freely, even appeared in public places. The people who rented him the apartment did not know his true identity".
He even gave public lectures and was a regular contributor to Healthy Life magazine, editor Goran Kojic said.
"The person I got to know was a person that everybody would like to be their friend," Mr Kojic told the BBC, adding that members of his family had died in the siege of Sarajevo.
"He was a highly cultured man, he was very tolerant, he had a sense of humour, he was very positive, he was very intellectual - so he was a great person."
Mr Kojic added that he never talked politics with Mr Karadzic; their conversations were limited to health.
"He walked freely in the city centre of Belgrade and no one knew it was him. I got the impression that this man did not fear anything."
Serbian intelligence officers were on the trail of Mr Karadzic's wartime military leader, Ratko Mladic, when they stumbled upon Mr Karadzic, said the office of Serbia's war crimes prosecutor.
Agents waited for the right moment when Mr Karadzic was alone and could be arrested without putting members of the public at risk, they said, and that moment came on a bus in a Belgrade suburb on Monday evening.
Mr Karadzic had last been seen in public in eastern Bosnia in 1996, and was previously thought to have hidden in Serb-controlled parts of Bosnia, as well as in Montenegro and Serbia.
Serbia's EU hopes
The arrest of Mr Karadzic and other indicted war criminals is one of the main conditions of Serbian progress towards European Union membership.
A new European-leaning government took office in Serbia about two weeks ago.
Serbian Foreign Minister Vuk Jeremic said Mr Karadzic's capture demonstrated the government's political commitment to EU membership.
After meeting Mr Jeremic in Brussels, EU Enlargement Commissioner Olli Rehn said the arrest had moved Serbia closer to EU candidate status.
Mr Karadzic has denied the charges against him and refused to recognise the legitimacy of the UN tribunal.
After the accord that ended the Bosnian war was signed in late 1995 in Dayton, in the US state of Ohio, the former nationalist president went into hiding.
International pressure to catch Mr Karadzic mounted in spring 2005 when several of his former generals surrendered, and a video of Bosnian Serb soldiers shooting captives from Srebrenica shocked television viewers in former Yugoslavia.
He was a close ally of former Yugoslav President Slobodan Milosevic, who was himself extradited to The Hague tribunal in 2001, but died in 2006, shortly before a verdict was due to be delivered in his case.
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