The 42-year-old escaped from custody at the Dunedin District Court on April 1 and was on the run for two days before being re-captured in a South Dunedin pizza store.
After his escape, the public was warned he was dangerous and volatile and should not be approached.
The officer in charge of Dunedin's frontline police, Inspector Alastair Dickie, investigated the incident and found a police officer was at fault.
"The prisoner wasn't escorted in the manner he should have been.
"He is required to be taken downstairs to the cells by a police officer.
"The officer involved sent him downstairs to meet another officer at the bottom."
However, when the first officer went back to the court room to collect some documentation, Carr went back up the stairs and was able to escape through an unattended court room with an unlocked door.
"He was able to just walk on out."
Inspector Dickie said the door was the only means of escape from the building for those in custody.
"Different agencies working in the court house have the ability to unlock the door, so from time to time, it can be accidentally left unlocked.
"But at the end of the day, the police made a mistake and staff have been instructed not to leave prisoners unattended in circumstances such as this.
"The officer involved has received some counselling."
Inspector Dickie said police and Dunedin court staff have proposed fitting a light to the door in question, which would alert staff if the door is unsecured.
In the interim, staff will check the door every 15 minutes to ensure it is secured.
