A registered nurse in Pennsylvania faces charges she administered lethal or potentially lethal doses of insulin to numerous patients — including a 104-year-old — at health care facilities over the past three years, prosecutors announced Thursday.

Heather Pressdee, 41, had been accused in May of killing two nursing home patients and injuring a third. She was arraigned Thursday on the additional counts, including two new homicide charges, and waived a preliminary hearing.

She was being held without bail at the Butler County jail.

James DePasquale, a defense attorney for Pressdee, said the new charges were not unexpected and that they are working to avoid a potential death penalty.

“At our urging, she has been very cooperative with the government,” DePasquale said.

The latest charges allege mistreatment of 19 additional patients at five care facilities since 2020. Along with two counts of first-degree murder, she was also charged Thursday with 17 counts of attempted murder and 19 counts of neglect of a care-dependent person.

Pressdee, a resident of Natrona Heights, Pennsylvania, allegedly gave excessive amounts of insulin to patients, some diabetic and some not. Pressdee typically administered the insulin during overnight shifts when staffing was low and the emergencies would not prompt immediate hospitalization, according to state Attorney General Michelle Henry.

Seventeen patients she cared for — ranging in age from 43 to 104 — have died, Henry said. Her nursing license was suspended earlier this year, not long after the initial charges were filed.

The alleged crimes happened while Pressdee worked as a registered nurse at five different facilities: Concordia at Rebecca Residence, Belair Healthcare and Rehabilitation (Guardian Elder Care), Quality Life Services Chicora, Premier Armstrong Rehabilitation and Nursing Center, and Sunnyview Rehabilitation and Nursing Center.

“The allegations against Ms. Pressdee are disturbing,” Henry said in a statement. “It is hard to comprehend how a nurse, trusted to care for her patients, could choose to deliberately and systematically harm them.”

According to court documents, Pressdee sent her mother numerous texts between April 2022 and May of this year 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 outside of health care facilities.

Charging documents from May say that 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.” Pressdee had held a number of jobs at nursing homes and facilities in western Pennsylvania beginning in 2018 for short periods of time, according to the documents.