The Department of Internal Affairs used facial recognition to ensure convicted killer Phillip John Smith did not have other passports in other names.
Smith flew to Brazil from New Zealand in November last year, while on temporary release from prison, after getting a passport in his birth name Phillip Traynor.
Documents obtained under the Official Information Act show the Department of Internal Affairs checked for passports under the name Phillip John Smith and his other alias Stacey Beavers shortly after he left the country.
It also ran facial recognition checks against the passports image database to make sure he had no other passports under another name - and found nothing.
The Department of Internal Affairs routinely compares facial characteristics to validate an adult applicant's passport renewal to detect indentity fraud.
A spokesperson said the use of facial recognition technology meant significantly less chance that a person could hold two passports in different identities.
Information given to Internal Affairs Minister Peter Dunne on Phillip Smith at the time, show the passport was cancelled on 11 November because of the arrest warrant issued while he was in Brazil.
Department Investigator, Ian Tingey, also said information contained on the passport application led him to believe the passport had been obtained through false representation.
"His address information provided on the application was not correct," he wrote.
Smith has pleaded not guilty to charges of escaping custody and making a false representation when applying for his passport. He is due in the Auckland District Court in March.
On Tuesday, Whanganui man Christopher Ryan Clifton pleaded guilty to helping Smith obtain the passport.
The Whanganui District Court heard the 25-year-old had become friends with Smith when they were inmates at Hawke's Bay Prison in 2008.
The court was told he received a call from Smith in June 2014, asking him to be a referee for the passport application.