A former Woodstock nurse admitted Thursday to using insulin to kill eight seniors and hurt six others while the vulnerable individuals were in her care, in part because she felt angry with her career and her life's responsibilities.

More than seven months after her arrest, Elizabeth Wettlaufer pleaded guilty to eight counts of first-degree murder, four counts of attempted murder and two counts of aggravated assault.

The crimes took place over the last decade in three Ontario long-term care facilities where Wettlaufer worked as a registered nurse, and at a private home.

The 49-year-old, who appeared in a Woodstock court, acknowledged under questioning from the judge that she used insulin in all 14 cases.

Prosecutors began laying out the details of each incident for the courtroom, which was packed with relatives and friends of her victims.

Reading from an agreed statement of facts, the Crown said Wettlaufer told police she knew that "if your blood sugar goes low enough, you can die." She also told police she had refrained from logging her use of insulin in order to avoid detection, court heard.

In at least one case, Wettlaufer was spurred to act by growing rage over her job and her life, which built up inside her until she felt an "urge to kill," the Crown told the court.

Wettlaufer deliberately injected James Silcox, an 84-year-old man with diabetes and Alzheimer's disease, with insulin the night of Aug. 11. 2007, "hoping he would die," the Crown lawyer said.

"It was his time to go because of the way he acted," the former nurse told police, according to the agreed statement of facts.

She also told investigators that afterwards, she felt "like a pressure had been relieved from me, like pressure had been relieved from my emotions."

Silcox was later found without vital signs by a personal support worker, court heard.

Wettlaufer also admitted to police that her dissatisfaction with her life led her to inject Clotilde Adriano with insulin, though Adriano survived.

Some family members of Wettlaufer's victims broke down in the courtroom as Wettlaufer entered her pleas.

Friends and relatives of the seniors who died had said earlier Thursday that they were warned the hearing would reveal information that may be difficult for them to handle.

Some, however, expressed relief that the case would come to a swift conclusion.

Andrea Silcox said before the court hearing that she was worried about what she would discover about her father's last moments, but said she'd be grateful to avoid a lengthy trial.

"I will forgive her, I have to forgive her...my father would want that," she said. "Forget? I'll never forget what happened."

Arpad Horvath Jr., whose father was also among Wettlaufer's victims, said everyone who lost a loved one will have to live with the pain forever.

"She took away my best friend and my hero and I can't forgive that," he said.

The police investigation into Wettlaufer began last September after Toronto police became aware of information she had given to a psychiatric hospital in Toronto that caused them concern, a police source has told The Canadian Press.

In October, Wettlaufer was charged in the deaths of eight residents at nursing homes in Woodstock and London, Ont. In those cases, police alleged Wettlaufer used drugs to kill the seniors while she worked at the facilities between 2007 and 2014.

In January, Wettlaufer faced six additional charges related to seniors in her care. Court documents allege Wettlaufer injected those six alleged victims with insulin.

Records from the College of Nurses of Ontario show Wettlaufer was first registered as a nurse in August 1995 but resigned Sept. 30, 2016, and is no longer a registered nurse.

She will be sentenced June 26 and 27.

(With files from the Canadian Press)