A nurse has been found guilty of murdering two elderly women at a nursing home on the New South Wales far north coast.

Megan Haines killed 82-year-old Marie Darragh and Isabella Spencer, 77, who were found dead at St Andrews Village nursing home in Ballina in May 2014.

The court had previously heard both women were injected with a lethal dose of insulin hours after Haines found out they had lodged complaints against her.

It also heard that Haines, while watching a crime show with her former partner, had boasted about using insulin to kill a person without being detected.

Marie Darragh (left) died in 2014. ( AAP: Facebook )

When giving evidence, the nurse, who pleaded not guilty to the murders, told the jury she could not remember the conversation.

However, she said she would sometimes discuss her nursing knowledge while watching similar TV shows.

The trial also heard that on the night before the victims died, Haines had been informed that she was the subject of several patient complaints.

She was questioned in detail about her movements at the nursing home on the night the women were killed, including which patients were given medication and when.

Haines said on the night of the deaths, she entered Ms Darragh's room, with another staff member after they heard noises.

The jurors took four hours to reach their verdict in the NSW Supreme Court.

As the verdict was handed down, Haines showed no reaction.

Verdict will help heal pain: Nursing home CEO

The CEO of St Andrew's Village Phillip Carter said he hoped the outcome would provide comfort to the victims' families.

St Andrews Village nursing home chief executive Phillip Carter and chair David Nunn. ( ABC News: Raveen Hunjan )

"Today's guilty verdict in the murder of two of our former residents is an important step in the healing process for our victims' family," Mr Carter said.

"Our thoughts and prayers are with the Darragh and Spencer families who have had to endure [the] pain and grief of losing loved ones in distressing circumstances and the subsequent burden of a trial."

Mr Carter added that he maintained full confidence in his staff.

At the hearing Haines' defence lawyer applied for a delay in sentencing proceedings so a psychological assessment could be completed.

A sentencing hearing was scheduled for December 7.