The session was meant to mark the final act of a decades-long legal process over the atrocities of the Bosnian and Croatian wars. Instead, it descended into chaos, confusion and, ultimately, death.

As judges at the International Criminal Tribunal for the Former Yugoslavia were in the midst of delivering rulings today over appeals related to Croatia’s involvement in the Bosnian conflict, one of the six defendants before the court suddenly drank what appeared to be a vial of poison and died shortly afterward, Croatian state television and a tribunal official said.

When judges announced that they had upheld a 20-year sentence against Slobodan Praljak, the former general addressed the bench in Croat. In a solemn voice, he said: “Slobodan Praljak is not a war criminal. I reject your judgment with contempt.”

Praljak then raised a small vial and drank from it. His lawyer called out, “Our client says he took poison.” Praljak was taken from the courtroom shortly afterward, and the hearing was suspended.

He was later pronounced dead and his body removed from the court building, a tribunal official said, speaking on condition of anonymity. Croatian state television said Praljak had died in a hospital in The Hague, citing unidentified sources close to him.

The presiding judge suspended the session after Praljak, 72, drank the liquid, and ordered curtains that divide the court from the public gallery to be drawn. Guards seized the vial used by the defendant. If tests prove the liquid was poisonous, officials will have to explain how he managed to smuggle it into the courtroom — proceedings at The Hague are typically tightly controlled.

The judges had upheld sentences on two of the six defendants before getting to Praljak, who had been sentenced for his involvement in an offensive against a Bosnian town.

The session was adjourned to an alternate courtroom, with a judge saying the original one was a crime scene. Sentences on the remaining three defendants were then upheld.

The hearing drew attention to Croatia’s often-overlooked role in the Bosnian war.

The tribunal has for the past 24 years largely focused on the dominant Serbian role in the conflict.

But Croatia, a range of trials at the tribunal have shown, also orchestrated a brutal campaign of ethnic violence to seize Bosnian lands once the Yugoslav federation began to disintegrate in 1991.