In a report into her death released today, Coroner Katherine Greig said Ms Kingi was let down on the night of her death.
After an inquest into her death there was one key recommendation which, if implemented, could prevent similar deaths, Ms Greig said.
"That is the length of time it can take to unlock a cell door during night watch hours in New Zealand prisons.''
Staff on the nightshift do not carry cell keys. They are held in a secure area for the safety of the prison officers.
An internal investigation led by Inspector of Corrections Louise MacDonald found prisons had decided what they considered an appropriate timeframe it took to retrieve keys; between four and 12 minutes.
But Ms MacDonald found having a system where it took 13 minutes to unlock a cell door was too long and the response timeframe in such circumstances should be no more than five minutes.
In her report today Ms Greig recommended to the chief executive of the Department of Corrections that the Prison Service set a benchmark which meets international standards.