(AP) – A registered nurse in Pennsylvania is accused of administering 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, was charged in May with killing two nursing home patients and injuring a third. She was arraigned Thursday on additional charges, including two new murder charges, and waived a preliminary hearing.

She was held without bail in the Butler County Jail.

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

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

The latest charges concern the mistreatment of 19 other patients in five nursing facilities since 2020. In addition to two counts of first-degree murder, she was also charged on Thursday with 17 counts of attempted murder and 19 counts of neglect of a person in need of care.

Pressdee, a resident of Natrona Heights, Pennsylvania, is alleged to have administered excessive amounts of insulin to patients, some of whom were diabetic and some of whom were not. According to Attorney General Michelle Henry, Pressdee typically administered the insulin during night shifts when staffing levels were low and emergencies did not result in immediate hospitalization.

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

The alleged crimes occurred while Pressdee was working as a 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 difficult to understand how a nurse entrusted with the care of her patients could choose to intentionally and systematically harm them.”

AccordinglyCourt documentsPressdee sent her mother numerous text messages between April 2022 and May this year in which she spoke to various patients and colleagues about her dissatisfaction and discussed potentially harming them. She also expressed similar complaints about people she encountered in restaurants and other places outside of health care facilities.

May’s charging documents state that Pressdee has a history of “being disciplined for abusive behavior toward patients and/or employees at each facility, resulting in her resignation or termination.” According to the records, Pressdee briefly held a series of jobs at nursing homes and facilities in western Pennsylvania starting in 2018.