In the last three years the International Residual Mechanism for Criminal Tribunals (IRMCT) has arrested two Rwandan genocide suspects and confirmed the deaths of four other fugitives, including Ndimbati.

In a statement U.N. prosecutors said they concluded Ndimbati died in 1997 in Rwanda.

"While the exact circumstances of his death have not been determined owing to the confusion and absence of order at the time, the evidence gathered by the office of the prosecutor demonstrates that Ndimbati did not leave the Gatore area, and that he was never seen or heard from again," the statement said.

Ndimbati, a Rwandan public official during the 1994 genocide, was accused of having personally organised and directed the killings of thousands of Tutsis and faced multiple genocide charges.

In all more than 800,000 Tutsis and moderate Hutus were slaughtered by Hutu extremists, led by the Rwandan army and a militia known as the Interahamwe, in 100 days in 1994.

The former U.N. tribunals for war crimes in Rwanda and Yugoslavia have been rolled over into a successor court that has offices in The Hague, Netherlands, and in Arusha, Tanzania.

There are no remaining fugitives from the Yugoslavia tribunal and now only two outstanding suspects for the Rwanda tribunal.

(Reporting by Stephanie van den Berg)