A Pennsylvania nurse who administered lethal or potentially lethal doses of insulin to numerous patients pleaded guilty to three counts of murder and other charges Thursday and was sentenced to life in prison.

Heather Pressdee, 41, was given three consecutive life sentences and another consecutive term of 380-760 years behind bars during a hearing in Butler, about 30 miles (48 kilometers) north of Pittsburgh. She played a role in the deaths of at least 17 patients who lived in five health facilities in four counties between 2020 and 2023, prosecutors said.

The victims ranged in age from 43 to 104. Coworkers often questioned Pressdee’s conduct and said she frequently showed disdain for her patients and made derogatory comments about them, authorities said.

Pressdee pleaded guilty to three counts of first-degree murder and 19 counts of attempted murder. She initially was charged in May 2023 with killing two nursing home patients and injuring a third,. Further investigation led to dozens of more charges against her. During a February hearing in which she argued with her attorneys, she indicated that she wanted to plead guilty.

The plea hearing was expected to last through Friday because several people wanted to give victim impact statements, officials said.

Prosecutors alleged that Pressdee, of Harrison, gave excessive amounts of insulin to patients, some diabetic and some not. She typically administered the insulin during overnight shifts, when staffing was low and the emergencies wouldn’t prompt immediate hospitalization.

Her nursing license was suspended early last year, not long after the initial charges were filed.

According to court documents, Pressdee sent her mother texts between April 2022 and May 2023 in which she discussed her unhappiness with various patients and colleagues, and spoke about potentially harming them. She also voiced similar complaints about people she encountered at restaurants and other places.

Pressdee had a history of being “disciplined for abusive behavior towards patients and/or staff at each facility resulting in her resigning or being terminated,” prosecutors said in court documents. Beginning in 2018, Pressdee held a number of jobs at western Pennsylvania nursing homes and facilities for short periods, according to the documents.