A Kiwi man jailed for blackmailing a wealthy Los Angeles businessman with claims of evidence showing an extramarital affair is now being electronically monitored by authorities using GPS.

The Herald on Sunday revealed Glenn Green was charged last year after an investigation involving New Zealand police and the Los Angeles police department.

The 49-year-old Aucklander was accused of making contact with the high-profile businessman in March last year.

The businessman, whose identity is suppressed, has a significant public profile and has been involved in the running and ownership of companies worth several billions of dollars, the Herald understands.

Green told the businessman's executive assistant he was in possession of videos and photos of the businessman engaging in a sex scandal, the Herald first reported.

He then demanded a large cash payment to stay silent or the images would be sent to the Los Angeles Times and People magazine.

The businessman then phoned Green, who repeated his threats and told the businessman he needed to pay up to avoid a scandal, court documents show.

However, despite the businessman blocking Green's phone number, he was bombarded over the next six days with 24 text messages and two voicemails from Green on a different phone.

Green also threatened to disclose the material he held in his possession to the businessman's wife, daughter and others.

These threats prompted the businessman to arrange for security at his home.

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In late March last year, the businessman received a handwritten letter from Green, which was accompanied by photographs of people, screen shots and New Zealand store advertisements.

Green again said in the letter that he would leak photographs and related information to the Los Angeles Times and People magazine should the businessman continue to refuse to pay him.

Court documents read that the businessman and his family have suffered "very considerable and long-lasting anxiety".

After police charged Green he later pleaded guilty to blackmail and was sentenced to 17 and a half months imprisonment in May.

However, he then appealed the several release conditions imposed on him by Judge Claire Ryan, which included a condition prohibiting Green from entering any internet cafe, public library or place of similar business where he could gain access to internet-capable devices.

There were also conditions requiring Green to submit to electronic monitoring using GPS technology and a condition prohibiting him from any employment or training, paid or unpaid, without the prior written approval of a probation officer.

Green has some 198 previous convictions offending including for assault, wilful damage, intimidation, speaking threateningly, assaulting police and resisting police.

He also has 35 convictions for breaching the terms of a protection order.

In addition, Green has several previous convictions for offending involving dishonesty and also has convictions for forgery and altering a cheque and fraudulent use of a document.

Green has further been convicted on eight occasions of misusing a telephone and using a telephone offensively. He has also been convicted for sending a threatening letter, making a false claim of fire, impersonating police three times, making a false statement that an offence had been committed, giving a false oath twice, perverting the course of justice six times, and engaging in criminal harassment eight times.

The latter convictions have led to Green being regarded by the courts media as a serial stalker.

When dismissing Green's appeal this month, Justice Graham Lang said the blackmailer "presents as a real risk of future offending through use of the internet".

"His previous convictions for similar offending and past record of failing to comply with court orders establish this risk beyond question."

Green, who represented himself at the September 2 hearing, argued the condition preventing him from entering an internet cafe, public library or place of similar business where he can gain access to internet-capable devices is ineffective.

He said if he wished to get on the net he could easily go to the address of a neighbour or a friend without being in breach of any release condition or without authorities knowing.

"I accept Mr Green's argument on this point as far as it goes. Arguably, however, it serves only to highlight the possibility that the present release conditions do not go far enough," Justice Lang said.

"They should arguably have prohibited Mr Green from being permitted to visit any address at which he might be able to obtain unmonitored access to a device capable of accessing the internet."

Green told the judge he was seeking a position as a mechanic in a garage or car repair business.

"I consider, for what it is worth, that the probation service should permit Mr Green to apply for such positions without being required to disclose his previous convictions so long as it can be sure the job will not permit him to have access to any internet-capable device," Justice Lang said.

"This does not detract in any way from Mr Green's general obligation as a prospective employee to honestly answer any questions an employer may ask about his past history."