When it comes to dealing with war crimes, Serge Brammertz is an old hand. The last high profile case he was in charge of was the UN investigation into the assassination of Lebanese ex-Prime Minister Rafiq Hariri. His mandate for that investigation ended on Dec. 31.

The 46-year-old, who also lead investigations of the war crimes committed in the Democratic Republic of Congo, Darfur and Uganda, succeeded Carla del Ponte as chief prosecutor of the UN war crimes court for the former Yugoslavia on Jan. 1.

Under del Ponte, the tribunal tried about 40 cases, including that of former Serbian President Slobodan Milosevic, who died before his trial could be completed.

Top high-profile suspects at large

Now the Belgian Brammertz has inherited the large task of tracking down and trying the two most wanted former Yugoslav war criminals: Ratko Mladic, the former Bosnian Serb military chief, and his then political boss Radovan Karadzic.

"The main challenge for Mr. Brammertz and for the war crimes' tribunal is the survival of the tribunal itself, because the two main suspects are not there," Belgian journalist Stefan Blommaert told Deutsche Welle.

"The work of the war crime tribunal finishes in 2010, so if the two main suspects, Karadzic and Mladic are not in The Hague by then, the image of the tribunal will be tarnished."

The pair has been indicted for genocide, war crimes and crimes against humanity over the bloody campaign of ethnic cleansing during the 1992-1995 war in Bosnia. But Serbia has never revealed Mladic's whereabouts, though he is believed to be hiding out in the country. Radovan Karadzic is also suspected of hiding somewhere in the Balkans.

Serbian help needed

"[The Serbian government's] co-operation became better but still they didn't catch Mladic," Blommaert said. "If you want to get Mladic in The Hague, you need the full co-operation of Belgrade and all the institutions in Belgrade."

Frustrated by the lack of cooperation by Serbia and other nations in the region to capture Karadzic and Mladic under international arrest warrants, del Ponte informed the UN earlier this year of her intention to leave the post that she has held since 1999.

While she is appointed the Swiss ambassador to Argentina, Brammertz will have his work cut out for him.

Though an internationally recognized expert, Brammertz is considered to be a bit of a bureaucrat, and one of his main tasks will be to make himself known in the Balkans, where the outspoken, media-savvy del Ponte had become a permanent fixture during her eight-year term, Blommaert said.

A distinguished carreer

Born in Eupen in the German-speaking region of Belgium, Brammertz has degrees in law and criminology from Belgian universities and was a professor of law at the University of Liege.

He started his career as a lawyer before quickly moving up in the ranks of the Belgian national prosecutor's office.

In 2002, Brammertz became federal prosecutor in Belgium. He is considered an expert in fighting cross-border organized crime, and international legal cooperation in the fields of terrorism, arms trafficking and human rights violations.