"In some ways I am shocked, but in some ways I wasn't," he said. "Basically, the whole trip sounded dodgy. He's quite a gullible man. He's mature in a lot of ways, but quite childlike in others."
Ashley de Malmanche said his father was "a bit of an internet dater" and had met a new woman about three months ago.
"She lives in South Africa or somewhere. She said she would pay for his trip. I said to him 'look, this is dodgy, people don't just do that kind of thing - there is no such thing as a free lunch'. But he went.
"He said he didn't have any clothes and she said not to worry, she would buy him some. She sent him the money for the tickets. He said he didn't have a passport so she sent him the money to get one ... that's why he didn't think it was a scam. He's been a bit silly."
Ashley de Malmanche said his father did not use methamphetamine or any other drugs except for painkillers. In 2002 he was working as a tree feller and a large branch struck him, resulting in serious back and neck injuries. He has been unable to do any physical work since, and is still in a lot of pain.
His son was worried that he would not have access to his medication in Bali.
"He's probably going to be in a lot of pain, even at home he is in pain. He's never used that stuff [methamphetamine]. He's a good person."
At a press conference in Denpasar yesterday the airport's head of customs office Budi Harjanto said de Malmanche was acting suspiciously when retrieving his luggage on Monday.
"From x-ray examination, we found something suspicious in his green backpack. After checking, we found a package with clear plastic wrapping, wrapped again with red plastic and brown duct tape. Inside, there's clear crystal weighed 1.709kg total."
A narcotics test confirmed the crystal was methamphetamine.
De Malmanche has been charged with a section of Indonesia's strict narcotics law carrying a maximum penalty of death and a one billion rupiah ($104,730) fine.
Mr Harjanto said de Malmanche was supposed to meet a woman at the airport. She was reportedly his fiancee and was on a different flight to Bali.
Mr Harjanto speculated that de Malmanche was set to marry the woman in Bali after meeting her in Hong Kong.
Last night Ashley de Malmanche was not sure what he could do to help his father. He did not know whether he would be allowed to contact his father - or how.
"There's not much we can do. He can't afford a lawyer and we won't be able to afford one either. I'm not too sure what we can do,' he said.
"This is the first time he has been out of the country, I think. To be honest, I would have tried harder to stop him from going if I thought he would actually do it - I didn't think he'd be able to get himself over there."
As of last night de Malmanche had not requested consular assistance from the Ministry of Foreign Affairs and Trade. The agency was aware of his arrest, but had not been contacted by him or any of his family.
Kiwi Leeza Ormsby was recently deported from Bali where she spent nine months in jail for possession of marijuana. Ormsby was in the notorious Kerobokan prison, where high-profile Australian drug smuggler Schapelle Corby served her sentence.
Who is Antony Glen de Malmanche?
Born in Dannevirke, Tony de Malmanche grew up in Palmerston North and attended Freyberg High School. He now lives in Wanganui. He has children from several relationships - the youngest of whom drowned in 2004 when he was just 7.
In 2002 de Malmanche was working as a tree feller when he was seriously injured. He was forced to rethink his life and enrolled at the Whanganui Learning Centre so he could retrain for a non-physical job.
In a testimonial on the centre's website, he said he had no school qualifications when he enrolled in their computer, numeracy and literacy course in 2011.
He said he was "so proud and confident" when he completed the course. He then went on to enrol at the Universal College of Learning to study towards a National Certificate in Mental Health Support Work. De Malmanche is listed as a beneficiary.
