Libyan officials have captured Seif al-Islam Gadhafi, a son of former leader Moammar Gadhafi who had long been described as his heir apparent. Officials said Saturday that he was detained in a town near the border with Niger.

Seif al-Islam's whereabouts had been unknown since August. He disappeared as National Transitional Council fighters closed on the remnants of Moammar Gadhafi's forces.

In June, the International Criminal Court in The Hague called Seif-al-Islam the “de facto prime minister” of Libya as it issued an arrest warrant for him. The ICC accused him of crimes against humanity.

The previous month, the ICC prosecutor said he had “direct evidence'' that Gadhafi, Seif al-Islam and Libya's chief of intelligence had ordered the use of live ammunition and heavy weapons against anti-government protesters. ICC judges said the three were criminally responsible for killing, wounding and imprisoning hundreds of civilians in the first two weeks of Libya's uprising.

Seif al-Islam is 39 year old. He has a doctorate from the London School of Economics and speaks flawless English.

In 1997, he founded the charity, the Gadhafi International Foundation for Charity Associations, which has intervened in various hostage situations involving Islamic militants and sent hundreds of tons of aid to earthquake-ravaged Haiti.

But as anti-government demonstrators took to the streets earlier this year, he took a new stance. In February, he made an extemporaneous speech on Libyan state TV blaming the uprising on drunken and drugged tribal factions acting on their own agendas. He also promised tens of thousands would die if protests continued, creating “a river of blood”.