The UN tribunal process to seek justice for the worst wartime atrocities in Europe since World War II ended on June 30, with verdicts in the retrial of two former Serbian security chiefs accused of running paramilitary death squads in the former Yugoslavia.

The UN International Criminal Tribunal for the former Yugoslavia (ICTY) sentenced 90 war criminals to prison terms before handing off to its successor in 2017.

But as its temporary successor, the International Residual Mechanism for Criminal Tribunals, issues its final-ever verdicts for crimes and atrocities stemming from the violent breakup of Yugoslavia in the 1990s, here are some of the precedents and signal moments in the history of one of the world's most dogged efforts at humanitarian justice.

1993: Creation Of The ICTY

The UN Security Council established the ICTY in 1993 in response to a commission's findings in which experts documented "horrific crimes" and "grave breaches" of the Geneva Conventions and other violations of international humanitarian law.

It was a conflict that had killed -- according to the best subsequent estimates -- at least 130,000 people across the former Yugoslavia and displaced millions more.

The council expressed hope that the prosecution of such crimes would help "stop the violence and safeguard international peace and security."

The result was Resolution 827, passed unanimously on May 25, 1993, which established the tribunal.

1998: Srebrenica As Genocide

The conviction of former Bosnian Serb commander Radislav Krstic cemented the tragic events in and around Srebrenica in July 1995 as genocide.

The brutality and audacity of the roundup and execution of more than 8,000 Bosnian Muslim boys and men by Bosnian Serb forces under the command of Ratko Mladic and Krstic had shocked the world.

Years later, the ICTY would hint at the significance of the decades-long international commitment to justice: "As their bodies fell into mass graves, the machinery of denial of those crimes was set in motion."

Krstic was convicted in 1998 of genocide for his role as commander of the Republika Srpska army's Drina Corps, a historic and rare international application of justice under the so-called Genocide Convention of 1948. A career Yugoslav military officer who lost a leg from a land mine after joining Bosnian Serb forces in 1992, he was ultimately sentenced to 35 years in prison.

The International Court of Justice (ICJ) also ruled in 2006 that the events at Srebrenica constituted genocide.

2001: Rape As A 'Crime Against Humanity'

The ICTY convicted three junior members of a Serb military unit in February 2001 of rape, torture, enslavement, and outrages upon personal dignity against women in what is now Republika Srpska, a predominantly Serb region of Bosnia-Herzegovina.

Dragoljub Kunarac, Radomir Kovac, and Zoran Vukovic were sentenced to prison terms of between 12 and 28 years for participation in a Serb campaign "to cleanse the Foca area of Muslims; to that end the campaign was successful. Even the town's name was cleansed."

Their cases marked The Hague tribunal's first convictions for rape and for enslavement as crimes against humanity, and the first such verdict in an international European court.

The court reasoned that rape had been "used by members of the Bosnian Serb armed forces as an instrument of terror."

The ICTY regards its role in prosecuting sexual violence in the former Yugoslavia as helping "pave the way for the more robust adjudication of such crimes worldwide."

"More than [one-third] of those convicted by the ICTY have been found guilty of crimes involving sexual violence," it says. "Such convictions are one of the tribunal's pioneering achievements."

2005: Final Indictments Issued

Indictments against former Macedonian Interior Minister Ljube Boskovski and a former senior police officer are issued in March 2005, marking the last prosecutions begun under the 12-year-old tribunal.

Boskovski was stripped of parliamentary immunity but later acquitted by the ICTY of all charges, which stemmed from a conflict in 2001 between Macedonian security forces and Albanian guerrillas seeking independence from Skopje.

The ICTY said at the time that its goal was to conclude all trials by 2008 and to cease functioning by 2011.

Instead, it would continue its work until 2017 and, even then, hand over its remaining work to the international "mechanism" for prosecuting crimes in the former Yugoslavia and in Rwanda, known as the MICT.

2006: Serbia's Milosevic Dies In Custody

Former Yugoslav and Serbian President Slobodan Milosevic died of a heart attack in his Hague prison cell in March 2006, five years into a trial that he regarded as illegitimate for his alleged efforts to "rid vast swaths of territory of non-Serbs."

The ICTY called the Milosevic trial "a turning point for international justice and of critical importance" to victims of his alleged crimes in the former Yugoslavia.

At the opening of his trial, Chief Prosecutor Carla Del Ponte called "this tribunal, and this trial in particular...the most powerful demonstration that no one is above the law or beyond the reach of international justice."

Milosevic was accused by prosecutors of crimes in Kosovo, Bosnia-Herzegovina, and Croatia.

His trial was formally concluded just weeks before a verdict was scheduled, and a Trial Chamber that reviewed the evidence concluded that "a reasonable judge could convict Slobodan Milosevic on all [major] counts."

2008: Kosovar Acquittals

In 2008, two prominent Kosovar guerrilla leaders were acquitted on war-crimes charges over their actions a decade earlier, during Kosovo's bloody war of independence from Serbia.

Like many of the movement's most powerful figures, Ramush Haradinaj and Fatmir Limaj had already become politicians in an emergent Kosovo.

And like a number of indictments, trials, and prosecutions, their cases raised widespread concerns of witness intimidation and violence to conceal wrongdoing in the Kosovo War, which killed an estimated 12,000 people.

The ICTY verdict in Haradinaj's case -- he would go back on trial and be acquitted again in 2012 -- would specifically cite a fear to testify among "many witnesses" in a pattern that still remains a problem.

Former Kosovar President Hashim Thaci and other senior ex-guerrillas are currently under indictment for serious wartime crimes in a case that prosecutors say is still plagued by trouble protecting witnesses and other external challenges.

2011: Croatian Leadership On Trial

The ICTY in 2011 convicted three Croatian generals of war crimes before reversing itself on appeal in a case that targeted independent Croatia's political and military establishments.

The indictments had alleged ethnic cleansing during Operation Storm in 1995 by Croatian forces against ethnic Serbs.

The convictions sent major shockwaves through Croatian society, which had consistently regarded Croatian actions in the region's conflicts as a response to Serb aggression.

Generals Ante Gotovina and Mladen Markac were charged and convicted of aiding and abetting hundreds of killings of Krajina Serbs and prisoners of war.

Their convictions were later overturned and both men were given a hero's welcome by the political and religious elite upon their return to Zagreb.

2016: Karadzic Conviction

The ICTY in March 2016 found former Bosnian Serb military and political leader Radovan Karadzic guilty of genocide, crimes against humanity, and other war crimes for a broad range of actions against Bosnians.

He was accused by prosecutors of grave breaches against the Geneva Conventions, including ordering and commanding the yearlong siege of Sarajevo, the Bosnian capital, as well as ordering the Srebrenica genocide after taking UN personnel hostage as Bosnian Serb forces surrounded that area.

Karadzic's escape from justice for more than a decade made him a hero in the eyes of some Serbs, but it was also blamed for stunting both the Bosnia and Serb regions' prospects for recovery.

He was eventually captured in July 2008 in the Serbian capital, Belgrade, where he had been posing at a clinic as a doctor of alternative medicine.

After his conviction and 40-year prison sentence were announced, the ICTY said its judgment "shows that is it possible to deliver" justice to "millions of victims" of conflicts around the world.

2017: Praljak Poisoning

Slobodan Praljak shocked the world and exposed a rare security flaw at The Hague with his suicide in court on live television in November 2017.

The former senior commander of the Croatian Defense Council, the de facto army of the Bosnian Croats' unrecognized republic between 1991-96, rose to declare, "Slobodan Praljak is not a war criminal. I reject this verdict, with disdain!" after the ICTY confirmed his 20-year sentence for war crimes against Bosnian Muslims.

Then, the 72-year-old former TV and theater director lifted a dark glass vial and drank what was later confirmed to be potassium cyanide, inducing heart failure. An investigation by prosecutors failed to determine how Praljak had obtained the poison.

In the area controlled by the self-proclaimed Croatian General Staff, prosecutors argued successfully that war crimes were committed that prosecutors concluded Praljak either ordered or ignored and should have stopped.

Tribunal prosecutors also blamed Praljak for one of the lasting symbols of the war's toll on the Balkans, the destruction of the iconic Old Bridge in Mostar.

June 2021: Final Judgment Against Ratko Mladic

In June 2021, the MICT upheld a life sentence originally handed down in 2017 against former Bosnian Serb military commander Ratko Mladic for genocide, crimes against humanity, and other war crimes.

Mladic was blamed by prosecutors for two of the most shocking events of the Bosnian War: the 1,425-day siege of Sarajevo and the Srebrenica massacre of thousands of Muslim men and boys.

Mladic had evaded capture for 16 years before Serbian police and special forces captured him in northern Serbia in 2011.