A family member says a former rebel leader serving a 50-year sentence in Rwanda for war crimes committed during Sierra Leone's decade-long conflict has died after a serious illness.

Alex Tamba Brima's wife, Margaret, said she was at his side when he died Thursday at a hospital in Kigali.

Brima, known as "Gullit," was a senior leader of the Armed Forces Revolutionary Council which overthrew Sierra Leone's government in 1997. He was indicted in 2003 by a special court set up following the diamond-rich country's conflict, in which about a half-million people died.

Brima was found guilty on 11 counts, including acts of terrorism, murder, rape and the use of child soldiers.

The U.N.-backed residual Special Court for Sierra Leone said it will look into the factors surrounding his death.