In October 2011, Walbran, a former head of the Australian International School in Jakarta, was extradited from Australia to Indonesia following a request by the country's government.
The next year he was jailed for the rape and molestation of Indonesian boys, some as young as 8.
He served two years of a three-year sentence before being deported back to Australia in April last year.
Walbran then flew to Thailand through New Zealand, using a Kiwi passport, which enabled him to avoid Australian travel alerts for convicted paedophiles. He also failed to complete the process of registration with Australia's National Child Offender Register, Thai investigators told AAP.
Prime Minister John Key said at the time he didn't know how Walbran obtained a New Zealand passport.
"My advice at this stage is Mfat [Ministry of Foreign Affairs and Trade] doesn't know about the individual," he said.
"It's quite possible that it's legitimate. There are people that [sic] have multiple passports because they have multiple citizenship. So there are lots of people who travel on both an Australian and New Zealand passport and might theoretically do that at one time.
"But if it's an illegal passport, that's a very different issue but I don't have any advice about that."