A large group of potential jurors in Ottawa were abruptly sent home today after a man accused of participating in the mass genocide in Rwanda did an about-face, electing to be tried by a judge alone at his war crimes trial.

Jacques Mungwarere, 39, is the second Rwandan to be prosecuted under Canada's Crimes Against Humanity and War Crimes Act, which was introduced in 2000 and allows for prosecution no matter where or when an alleged war crime may have been committed.

The first person prosecuted under the act is Desire Munyaneza, who was sentenced to life in prison in 2009.

The RCMP arrested Mungwarere in 2009 in Windsor, Ont. Nearly 800,000 members of Rwanda's Tutsi minority and moderates from the Hutu majority were killed during a 100-day period.

Mungwarere's case was set to be relatively unique among war crimes trials in that he had chosen to have his case heard before both a judge and a jury. War crimes cases are almost exclusively presided over by judges.

Rwandan officials allege Mungwarere, a former schoolteacher, led or participated in mass killings of civilians, including notorious massacres in two churches and a hospital in Kibuye.

He was tracked beginning in early 2003 after being recognized by a childhood friend from Rwanda on a city bus in Windsor, where he settled after immigrating to Canada in 1998.