A homicide detective told her they were there following the deaths of two women at St Andrews Village aged care, where Ms Haines had recently landed a job as a registered nurse.

The NSW Supreme Court has heard that Ms Haines was not told how those women had died.

Yet during an intercepted phone call to a friend a day later, Ms Haines allegedly knew the elderly residents had been given the wrong medication.

"They said on Saturday there was medication given to some patient or whatever," she said in the conversation played during her trial on Thursday.

"Apparently the patients were actually given wrong medication."

The Crown alleges that Ms Haines, 49, shouldn't have known about those details stemming from the alleged murders at the Ballina nursing home days earlier.

The South African-born nurse is accused of injecting insulin into Marie Darragh, 82, and Isabella Spencer, 77, at the Ballina nursing home after learning she had been the subject of complaints.

Ms Haines, who has pleaded not guilty to murder, had been working at the facility for about a month before the women died.

After being at the centre of three misconduct investigations in Victoria, restrictions attached to her nurses registration meant her employer had to provide six-monthly performance reports.

On May 9, 2014, as she clocked on for her night shift, Ms Haines learnt she was targeted with complaints again.

A manager told her two women had complained while a third complaint was pending, the court has heard.

The next morning Ms Darragh and Ms Spencer were found in comatose states in their beds.

Staff initially thought they had suffered strokes but tests later revealed they had insulin in their systems.

The court heard Ms Haines was meant to be at a meeting with St Andrews management on May 13 to talk about the complaints made.

During a conversation with a woman from an employment agency that day, Ms Haines asked for a support person to be at the meeting with her and described the complaints as minor.

"It's probably minor complaints but I still need to go to the meeting and see what happened," she said in a recorded phone call.

"I don't know if I should resign from this place or see if I can make it work or whatever."

Ms Haines also said she had been to "one of these meetings before" and it could escalate very fast.

"Before you know it the nurses board knows there has been a complaint about you," she said.

The trial continues.