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The arrest of Radovan Karadzic takes Europe a further step towards closing the bloodiest chapter of violence in its post-World War II history and reflects the European Union's allure for the fragile states of the east.
The Bosnian Serb leader, 63, had been on the run for 13 years, and suspicions run deep that he escaped justice thanks to support among Serbian politicians and the military.
Karadzic had grown a long, white beard to conceal his identity and had lived freely for months in the capital before being arrested.
"His false identity was very convincing," said Vladimir Vukcevic, Serbia's war crimes prosecutor who coordinated the security forces arrest. "He had moved freely in public places."
While on the run in Serbia, the world's top fugitive worked on a private clinic and wrote for a Belgrade magazine, according to Serbian officials. Karadzic also lectured about meditation at a May festival in Belgrade.
To do all this, Karadzic used a false name: Dragan Dabic, government minister Rasim Ljajic said. Ljajic also displayed a recent photo of an unrecognizable Karadzic with long white beard and gray hair.
He was arrested only two weeks after a new Government took office in Serbia - one dominated by the pro-Western Democratic Party of President Boris Tadic, who has made membership of the EU a cornerstone of his policies.
In April, before the elections, the EU held out the ultimate prospect of membership of the world's biggest trade bloc, dangling a precursor deal called a stabilisation and association agreement.
But the accord has remained suspended until Belgrade achieves "full co-operation" with the International Criminal Tribunal for the former Yugoslavia (ICTY).
Brussels has spelled out that this meant handing over Karadzic and the Bosnian Serb military chief Ratko Mladic, 65, like Karadzic accused of genocide and suspected of being harboured by Serbia. The clock had started to tick for The Hague-based ICTY, whose work must wind up in 2010.
Analysts had doubted whether the new Government had much scope to tackle the issue of the war criminals. The pair have hero status among hardline nationalists and the rise of Kosovo, a Serbian province, to independence under EU tutelage has stoked resentment among many Serbs.
The coalition includes the reformed Socialist Party of late President Slobodan Milosevic, who died in custody in The Hague in 2006. The new Interior Minister, Ivica Dacic, is head of the Socialists.
Despite this, the new Government in Belgrade began a series of discreet changes. Last week, it was announced that the head of Serbian intelligence, Rade Bulatovic, had been replaced - a move that came ahead of a scheduled visit today by the tribunal's chief prosecutor, Serge Brammertz - and that an entrenched criminal gang with links to the old elite, the so-called Jitka clan, was facing a crackdown.
The EU has praised Karadzic's arrest but kept up the pressure for Serbia to end its pariah status.
"It marks an important step on the way to Serbia's drawing nearer to the European Union," the EU said in a statement.
European Commission President Jose Manuel Barroso added: "It proves the determination of the new Serbian Government to achieve full co-operation with the ICTY. It is also very important for Serbia's European aspirations."
The 27-nation EU is mired in political problems after plans to overhaul its decision-making institutions were rejected by Irish voters in a referendum. But to the poor, recently democratised states of central and eastern Europe and the Balkans it remains a beacon of prosperity and stability.
Serbia was once one of the wealthiest and most culturally vibrant economies of the Balkans but is now among the poorest and most hermetic.
It has watched as countries of the former Soviet bloc and Yugoslavia have moved towards membership of the elite club.
This has opened the way to agricultural and industrial subsidies, a barrier-free internal market of 500 million people, educational exchanges and labour mobility - a new dawn for economies that were backward and enclosed.
