REUTERS - A Canadian nurse has pleaded guilty to using drugs to kill eight elderly patients in long-term care facilities over seven years, Canadian media reported on Thursday.  Elizabeth Wettlaufer was accused of killing five women and three men in the Ontario towns of Woodstock and London between 2007 and 2014. The dead ranged in age from 75 to 96. The nurse admitted in court that she fatally injected the victims with insulin for no medical reasons, Canadian media at the provincial courthouse said. Ontario's Ministry of the Attorney General was not immediately able to confirm the plea.–Ottawa

Wettlaufer, whose motive had been unclear, pleaded guilty to eight counts of first-degree murder, four other counts of attempted murder and two counts of aggravated assault. She could face life imprisonment when sentenced.

The criminal case is the largest in Ontario since 2006, when five men were charged with murdering eight biker gang members. They were convicted and sentenced to life in prison.

Mass killings are uncommon in Canada. In 1997, a Canadian doctor was charged with murdering a terminally ill cancer patient. A judge later threw out the case.