Former Bosnian Serb military chief Ratko Mladić is due to hear a judgment on his appeal against genocide, war crimes and crimes against humanity.
Mladić, known as the "Butcher of Bosnia" was convicted in 2017 of crimes during the Bosnian War and sentenced to life imprisonment.
The army chief had led troops responsible for a string of deadly campaigns, including the 1995 Srebrenica massacre and the siege of Sarajevo.
On Tuesday, United Nations judges will decide to either uphold or overturn his convictions, although the former military chief is unlikely to walk free.
The verdict in Mladić's appeal case will effectively conclude UN prosecutions for crimes committed during the 1992-95 war, which killed more than 100,000 and left millions homeless.
More than 25 years after the Srebrenica massacre, Mladić will appear before The Hague court for the ruling.
He was found guilty of genocide for leading the 1995 massacre of more than 8,000 Muslim men and boys in the eastern enclave of Srebrenica, the worst massacre on European soil since World War II.
Widows and mothers of victims will also be in court to hear the judgment by a five-judge panel led by Zambian Presiding Judge Prisca Matimba Nyambe.
Mladić has also been convicted of other crimes including persecution, extermination, murder and terror. His former political leader, Radovan Karadzic, also was convicted of the same crimes and is serving a life sentence.
Mladić was though acquitted of a second genocide charge linked to a campaigns to drive non-Serbs out of several towns early in the war. Prosecutors have appealed that acquittal.
After the war in Bosnia ended, Mladić went into hiding before he was finally arrested in 2011 and handed over to the International Criminal Tribunal for the former Yugoslavia.
The U.N. tribunal has since shut its doors. Mladic’s appeal and other legal issues left over from the tribunal are being dealt with by the U.N.’s International Residual Mechanism for Criminal Tribunals, which is housed in the same building as the now-defunct court for the former Yugoslavia.
Mladic and his legacy still divide Bosnia, with Bosniak Muslims viewing him as a villain and war criminal while many Bosnian Serbs still consider him a hero.