A former Canadian long-term care nurse pled guilty to eight counts of first-degree murder, four counts of attempted murder and two charges of assault on Thursday.

Elizabeth Wettlaufer, 49, was originally charged in October for the death of eight residents. In January she was additionally charged with the attempted murder of six different residents and two aggravated assaults.

She worked at long-term care facilities in southwest Ontario over seven years as a registered nurse overseeing the night shift.

Wettlaufer used insulin pens on residents at lethal doses, killing eight residents and seriously harming the others.

She said in court that she felt a “red surge” before she killed a resident and that her actions were often spurred by a growing rage over her job and life, according to a CBC article.

Wettlaufer had been registered as a nurse since 1995. In September, she resigned after Toronto police began investigating her following an admission Wettlaufer made at a psychiatric hospital.

She waived her right to a preliminary hearing in April. Sentencing is expected in late June.