Ruth Alison McKay, 90, vanished from her room at the Goodwin Ainslie aged care facility for an unknown period of time before staff realised she was missing about 7.40am on January 17, 2015.

Mrs McKay was found a short time later lying in dried blood, with a cut on her head, underneath an ornamental car in a secure courtyard.

She died in Canberra Hospital six days later, with a post-mortem examination finding her medical cause of death to be a form of pneumonia.

At an inquest into Mrs McKay's death this week, aged care facility staff have given conflicting evidence, with one staff member claiming to have seen Mrs McKay in bed as late as about 5am and another saying it appeared her bed had not been slept in.

Jeffrey Shelley, Goodwin Ainslie's residential operations manager at the time, told the inquest on Wednesday that he believed every room in the memory support unit, where Mrs McKay lived, had in-built sensor technology designed to alert staff to residents' movements.

Mr Shelley said while it was generally best practice to have the in-built system turned on, it was not a "clinical directive" at the time.

However, counsel assisting the coroner, Sarah Baker-Goldsmith, said Mrs McKay's care plan did include a directive that a sensor mat be used in her room.

Ms Baker-Goldsmith told Mr Shelley electronic logs showed no alerts from Mrs McKay's room during the overnight period before she was eventually found outside.

She repeatedly asked Mr Shelley whether the internal investigation he conducted had determined if the required sensor was turned on, or even in Mrs McKay's room at the time in question.

Mr Shelley said he had not made any notes about the sensor not being present, but he was unable to say that it was.

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Mr Shelley also denied allegations made by nurse Marco Arquero, who previously told the court that Mr Shelley had warned him he may lose his job if he spoke to the police.

Mr Shelley said he had only reminded an "emotional" Mr Arquero of his confidentiality obligations to residents, and of the employee assistance program in place.

But he admitted his communication style could be "unique", and "the message may not have been delivered or received".

Mr Shelley's boss at the time of the incident, Robyn Boyd, told the inquest several changes were later made at the facility, including the removal of the ornamental car and the enhancement of lighting in the courtyard.

Ms Boyd said these were elements of a collective Goodwin investigation, but Ms Baker-Goldsmith suggested they were actually responses to an investigation.

Ms Boyd insisted they were part of the investigation, because there was no way of truly knowing how and when Mrs McKay came to be underneath the ornamental car, and the facility's response was therefore about "what might have happened".

"How can I know what happened?" Ms Boyd asked. "I wasn't there."

Ms Boyd also told the inquest she did not consider there to be a deficiency in the facility's systems if Mrs McKay had gone into the courtyard after 5am, when a staff member had last reported seeing her in bed, and then spent hours outside unsupervised.

She said had a staff member seen Mrs McKay trying to go outside at that time of the morning, they would have encouraged her to stay inside, but aged care was "about supporting people to live as independently as possible".

"We don't restrict and restrain people," Ms Boyd said.

"If Ruth chose to walk out in the garden, she's free to make that decision."

Ms Boyd also agreed that she did take back a copy of a statement Mr Arquero had given to a police officer at the aged care facility, but she claimed that after looking at the piece of paper she gave it back to the police.

The inquest, before Coroner Louise Taylor, continues.