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(Reuters) - A Canadian nurse pleaded guilty on Thursday to using insulin to kill eight elderly patients in long-term care facilities over seven years, the Crown prosecutor said.

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.

Wettlaufer admitted in court that she fatally injected the victims with insulin for no medical reasons, the prosecutor said in an email.

Wettlaufer, whose motive is 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 in prison when sentenced at a later date.

The advocacy group CARP, formerly known as the Canadian Association of Retired Persons, on Thursday called for a public inquiry into the abuse of long-term care residents in Canada, saying the Wettlaufer case was part of a “growing crisis.”

“For years, we’ve heard stories about residents who suffered or die (due) to neglect, abuse and violence in facilities meant to be providing care,” said Wanda Morris, vice president of advocacy for CARP.

Homicide cases with multiple victims are uncommon in Canada. The Wettlaufer case is the largest in Ontario province since 2006, when five men were charged with murdering eight members of a biker gang. They were convicted and sentenced to life in prison.