Ruth Alison McKay, 90, died at Canberra Hospital in January 2015, six days after staff at the Goodwin Village Ainslie aged care facility found her lying underneath an ornamental car in a secure courtyard.

Counsel assisting the coroner, Sarah Baker-Goldsmith, said the inquest would investigate the manner and cause of Mrs McKay's death, and particularly how she left her room and ended up outside.

Ms Baker-Goldsmith said the inquest would also consider staffing levels in the aged care home's memory support unit, the facility's processes around room exit alarms and reporting of significant incidents, and any matters of public safety.

In her opening statement on Monday, Ms Baker-Goldsmith told the ACT Coroners Court that Mrs McKay and her husband Douglas arrived at the aged care facility in 2009. The couple was initially housed in the independent living section.

In July 2013, six months after Mr McKay's death, Mrs McKay was assessed as having advanced dementia and moved to the memory support unit. Ms Baker-Goldsmith said Mrs McKay remained "in general good health" until the period immediately before her death.

About 7.40am on January 17, 2015, staff at the aged care facility went to check on Mrs McKay and found she was not in her room.

A short time later, they found Mrs McKay lying under an ornamental car in the memory support unit's secure courtyard. She was in her night gown and had a large cut on the left side of her head. While not trapped under the car, Mrs McKay was unable to lift herself up.

"A large pool of dried blood was located on the concrete outside and to the left of the glass exit door, and blood spots led in a direction from the large pool towards the car," Ms Baker-Goldsmith told the court.

"A dried blood pool was observed underneath the car where Mrs McKay's head was resting, as well as vomit observed on the concrete.

"In addition, bloody finger marks were observed on the left door of the car, as well as on a metal pole supporting the car port structure which covered the car."

Mrs McKay was taken to Canberra Hospital, but died six days later.

Ms Baker-Goldsmith said a post-mortem examination found Mrs McKay's medical cause of death to be pneumonia. A forensic pathologist noted that factors including hypothermia and Mrs McKay's fall may have contributed.

The inquest heard on Monday from two former staff members who worked at the aged care facility during the overnight shift beginning on January 16, 2015.

Poniman Tju, the team leader, said he had seen Mrs McKay in bed at 2.10am on the morning she was later found to be missing.

He said he only checked on Mrs McKay once during his shift, but personally checked the external doors early in the shift and made sure they were locked.

Mr Tju said Mrs McKay was known to "wander". He reported an incident on January 4, 2015, when he said Mrs McKay had spoken of needing to start a car so she could go and see her parents.

Mr Tju also said Mrs McKay's care plan included a sensor mat, designed to alert staff if she got out of bed during the night. He said he did not receive such an alert during the shift in question.

The inquest, before Coroner Louise Taylor, continues.