The main organizer behind the 1994 slaughter of more than 500,000 people in Rwanda was convicted of genocide Thursday and sentenced to life in prison, the most significant verdict of a UN tribunal set up to bring the killers to justice. Col. Theoneste Bagosora was found guilty of crimes against humanity, and the court said he used his position as the former director of Rwanda's Ministry of Defense to direct Hutu soldiers to kill Tutsis and moderate Hutus. Bagosora also was found responsible for the deaths of former Rwandan Prime Minister Agathe Uwilingiyimana, a moderate Hutu, and 10 Belgian peacekeepers who tried to protect her as she was killed at the outset of the genocide. Bagasora said nothing as the verdict was delivered, and there was complete silence from the scores of people who had packed into the aisles of the tiny courtroom to hear the judgment. His conviction was welcomed by genocide survivors, who still live uneasily among perpetrators in Rwanda's green hills nearly 15 years later. Some 63,000 people are suspected of taking part in the genocide, although many of them have been sentenced by community-based courts, where suspects were encouraged to confess and seek forgiveness in exchange for lighter sentences. "Bagosora ... is the person behind all the massacres," said Jean Paul Rurangwa, 32, who lost his father and two sisters. "The fact that he was sentenced to the biggest punishment the court can give is a relief." The Tanzania-based International Criminal Tribunal for Rwanda was set up by the UN in 1994 to try those responsible for the killings and had its first conviction in 1997. There have been 42 judgments, of which six have been acquittals. It does not have the power to impose the death sentence. More than 500,000 minority Tutsis and political moderates from the Hutu majority were killed in the 100-day slaughter organized by the extremist Hutu government then in power. Government troops, Hutu militia and ordinary villagers spurred on by hate messages broadcast over the radio went from village to village, butchering men, women and children. Reed Brody, a specialist in international justice for Human Rights Watch, said the sentence sent a clear message to other world leaders accused of crimes against humanity and genocide, like Sudanese President Omar al-Bashir. "It says watch out. Justice can catch up with you," Brody said. "The authors of genocide can and will be punished by the international community." According to the indictment, Bagosora had participated in international talks arranged in the early 1990s with the aim of ending Rwanda's long-simmering political crisis. Bagosora grew angry with government delegates he deemed soft on Tutsi-led rebels and said he was returning to Rwanda to "prepare the apocalypse," the indictment quoted Bagosora as saying. At the time of the genocide, he was the second-highest ranking official in the defense department. The killings began on April 7, 1994, the day after the plane carrying ethnic Hutu President Juvenal Habyarimana was shot down by unidentified attackers on its approach to Kigali airport. Bagosora was commander of the Kanombe air base in Kigali when the president's plane went down. Hours after the crash, militants from the Hutu ethnic majority known as Interahamwe set up roadblocks across Kigali and the next day began killing Tutsis and moderate Hutus. The slaughter eventually ended after Tutsi rebels invaded from neighboring Uganda and drove out the genocidal forces. Also Thursday, former military commanders Anatole Nsegiyumva and Alloys Ntabakuze were found guilty of genocide and sentenced to life in prison. The former chief of military operations, Brigadier Gratien Kabiligi, was cleared of all charges and released. Earlier in the day, Protais Zigiranyirazo was convicted of organizing a massacre in which hundreds of Tutsis died, and was sentenced to 20 years. He has already served seven.