He was convicted of unlawful sexual connection with a girl under 12, attempted unlawful sexual connection with a boy under 12, indecently assaulting boys and girls under 12 and permitting a girl under 12 to be indecently assaulted.
In 2011 he was jailed for 2 years and 9 months after he was convicted of possessing objectionable material.
Judge Ronayne said Bettridge had another 22 similar convictions.
When he was sentenced for the 2011 offending he was placed on the Child Sex Offender Register.
When such offenders leave prison they must, by law, report personal information to the register, including their address, their motor vehicle details, details of children living in their household, internet provider details and any websites they administer.
They must also notify police of any changes of these details, within 72 hours of the change.
In October 2016 Bettridge was released from prison and given notice of his reporting obligations.
The supervision order had been put in place earlier - ordered by the courts at the request of the Department of Corrections.
One of the conditions of the order was that Bettridge not use the internet or possess any internet-capable device without prior written approval, and under pre-approved supervision.
In October 2018 Corrections, police and Department of Internal Affairs staff visited Bettridge's apartment in central Auckland.
The purpose of the visit was for authorities to assess any devices Bettridge had to ensure he was abiding by the supervision conditions.
Bettridge arrived home soon after and he was caught out on a string of offending.
First he revealed that he had three hard drives.
He claimed he had found the hard drives in a rubbish bin at the apartment complex and took them, intending on "disposing of them" later.
When asked if he had any other devices he was not allowed he said he wanted to "come clean" and revealed an internet-capable cellphone hidden under a pile of clothes on his bed.
He also revealed he had viewed pornographic images of children on the phone which he downloaded from the internet.
All but five of the images depicting naked children had been deleted.
Bettridge had purchased the cellphone from a Queen St store.
He accessed the Wi-Fi at his apartment building by "hanging around" the security office at a time when he knew work was being done on the internet service.
In doing that he was able to overhear the wifi password and used it to connect the cellphone to the internet.
Bettridge also set up a Gmail account, joined a number of social media sites 0 and a Russian dating site.
After all of this was exposed, Bettridge was arrested and charged.
He told police he "accepted" his offending and he was "apologetic" for his actions and "for the people he let down".
Bettridge pleaded guilty to all charges and was sentenced on March 26.
Judge Ronayne said his explanation about the hard drives was "wholly unbelievable".
"If it's true, you were taking rubbish out of the rubbish bin to then put it back in the rubbish bin - that is nonsense," he said.
"You explained to the probation officer that you first used the phone to look at YouTube videos, followed by adult pornography, then photos of teenage girls in bikinis.,
"Then you actively sought out child pornography and photographs of nude children.
"You also told the probation officer that you had taken a SkyTV box, iPods, phones and hard drives… There was a high level of preoccupation and deviancy.
Judge Ronayne said Bettridge had "significant and serious" previous convictions and even though he had participated in two child sex offender treatment programmes his most recent offending showed an escalation in his risk level.
"You did not express remorse for the victims of your offending - rather you expressed disappointment in yourself and the support people that you let down." he told Bettridge.
"Almost more concerningly… you reached out for professional support and completed 10 individual treatment sessions with a departmental psychologist between 21 June and 19 September 2018.
"You are said to have, during that period, used a high level of impression management - demonstrating superficial compliance and manipulation."
Judge Ronayne said Bettridge's risk of reoffending and harming others was deemed high.
"You, Mr Bettridge, seem to have no appreciation that you continue to objectify and sexually victimise young children," he said.
"As I assess the situation, you have at the present time almost no prospect of proper rehabilitation."
Judge Ronayne said Bettridge's offending was "thoroughly premeditated" and his explanation was "ludicrously unbelievable".
"Your offending actually victimised the children in the images," he said.
"Without deviants like you, there would not be the same appetite to abuse those children and record the abuse and upload the abuse.
"You might not think it is abuse but it is - even to create an image of a naked young girl."
Judge Ronayne said Bettridge's cooperation with authorities on the day they came to his apartment was "illusionary" and he only "came clean" when faced with "inevitable discovery".
"True remorse on your part is entirely absent," he said.
"You, Mr Bettridge, remain a danger to the community and a danger to our most vulnerable and as I have said your rehabilitation prospects are presently minimal."
He considered whether Bettridge could be sentenced to home detention - but dismissed the notion.
"Beyond mere denunciation and deterrence I have to consider protecting the community," said Judge Ronayne.
"I have to consider the victims interests because they are victims of your offending.
"I need also to consider the need to hold you to account and promote in you - perhaps forlornly - a sense of responsibility which is inherently absent.
"Home detention would be a patently inadequate response."
He sentenced Bettridge to 1 year and 1 month in prison.
