To meet Arkan face-to-face was a chilling experience.

It was an autumn evening in the town of Bijeljina in north-east Bosnia three years ago.

He had just appeared at an election rally for his party of Serbian Unity.

Although he had swapped his battle fatigues for an expensive suit and made a credible politician with his clean-cut looks and boyish smile, he gave off an almost tangible air of menace.

He had not yet been indicted for war crimes by The Hague tribunal - that came in 1997 - but he was already infamous for his role at the cutting edge of what came to be known as ethnic cleansing in both Croatia and Bosnia and later, allegedly, in Kosovo - although he denied that.

Bijeljina was one of the two towns in Bosnia, with Zvornik, which Arkan's paramilitary Tigers stormed at the beginning of the Bosnian war.

Many Muslims and Croats were murdered, it is believed at the hands of the Tigers.

When I asked him whether he had committed war crimes in this very town, Arkan's mask slipped. He angrily denied that what he did were war crimes.

"We were simply defending our fellow Serbs against the Muslims," he said.

His eyes conveyed even more menace than his words.

Arkan - real name Zeljko Raznjatovic - told me he owned three businesses, including a clothing factory.

In reality his links with organised crime were well-known, as were his ties to the intelligence services in Belgrade, from whom the Tigers obtained most of their equipment and supplies.

He gained celebrity status in Serbia, not for his military exploits, but for his lavish wedding to the pop star Ceca and for his ownership of the Belgrade Obilic football club.

Vital witness

Even before his role in the Yugoslav wars Arkan was notorious as a gangster and bank robber.

He was wanted by Interpol in several western European countries, where it is thought he furthered his links with the Yugoslav security services as their hired killer.

Whoever killed Arkan - and there are many possible suspects - has removed one of The Hague's most wanted men - but at the same time one vital witness as to who in Belgrade gave the orders for some of the worst war crimes in recent European history.