A clairvoyant who stole more than $250,000 from an elderly couple's bank account has lost his appeal for continued name suppression.

Terence John Harnett, 68, a clairvoyant of Blenheim, was convicted on a representative charge of theft by a person required to account, and a representative charge of theft by a person in a special relationship.

The former Nelson man was sentenced in November at the Blenheim District Court to 11 months' home detention and 150 hours' community work.

He is to serve the home detention sentence at Seaview, a Picton rest home, because he suffered from cognitive impairment.

A police summary of facts said Harnett, previously an accountant, was a family friend and managed the Nelson couple's accounts because of their ill health.

A daughter of the couple suspected the man, who she had known for 30 years, had taken large sums of money from her parents bank account while they were living in a rest home.

She said on Monday that because Harnett had a jail sentence of 23 months reduced because of dementia, he should have been put in a dementia ward, instead of being put in a rest home surrounded by more elderly people.

"It would reflect the severity of his crime ... he's a con man," she said.

A Seaview rest home manager said she was not concerned Harnett could reoffend because his mental impairment was severe.

"He is suffering and he has been in care for quite some time."

The couple's daughter discovered money missing from her parents' joint account last year when her father's retirement home bill went unpaid and was taken to court.

She was given the ability to manage her parents' accounts by the court so she could investigate where the money had gone. It was around that time that Harnett left Nelson.

"He had left my father $8000 in debt ... the reality is, after uplifting my father's documents, I could see exactly what had happened."

She was distrustful of Harnett from the beginning because he was a "terrible" clairvoyant, she said.

"I had arguments with my family about it ... I'd watched him do readings and they were never correct. He'd do those feel-good readings on TV. It was pathetic."

Harnett advertised online offering business and spiritual advice, a "professional business mentor service" and as a motivational speaker.

He went to the rest home regularly to have the woman's father sign blank cheques to pay for expenses and for his own personal use.

He also gave the couple an "appointment of agent" form to sign entitling him to operate as an agent for all their accounts, which gave him control of all cheque books in their name and allowed him to obtain the complainants father's signature on blank cheques.

"They should never have been signing anything like that without a lawyer present."

For 13 years, Harnett used pre-signed cheques to take large sums of money from the couple's bank account for his own use, without authorisation from the parents, or other family members.

The defendant wrote out cheques totalling $252,210 between 1998 and 2010.

The couple's daughter said her parents' financial losses went well beyond what was taken by pre-signed cheques. He invested more than $350,000 of their money in a failed high-risk ponzi scheme investment and countless bills went unpaid and incurred further interest, she said.

The woman said she was concerned that Harnett was to serve home detention at a place where he could continue stealing from elderly people.

It was "ridiculous" that he would be serving his sentence among the elderly when it was the elderly he had taken advantage of, she said.

"That sentence doesn't seem like a deterrent to anybody. If he was in a dementia wing I would feel so much happier, I really would. Then I'd know other people wouldn't be at risk."

"For a 68-year-old who's already in a rest home, who's got no friends left, to be sentenced like that; his only punishment now is the 150 hours' community service, all his meals cooked for him. It's nothing. It's completely the opposite of jail."

The complainant's father died three days before Harnett's sentencing.

"My father was so proud to have money put aside for us when he died ... I didn't have the heart to tell him what happened to it," the woman said.

Harnett attempted to pay back some of the money between 2001 and 2006, but only after the woman threatened to check on the accounts when unpaid bills were sent to her address.

In October 2011, he repaid a total of $18,800 into the account.

He said he took the money from their accounts as advanced payment and planned to pay it back.

Judge Tony Zohrab said Harnett betrayed their trust.

"You were at their house having Christmas dinner while at the same time you were robbing them blind.

"It was not a momentary error of judgement. You were well practiced at dishonesty. Your victims were vulnerable ... and you had the opportunity of having the time of your life."

Harnett's mother re-paid $45,000 but Zohrab could not order full reparation because it was unlikely it would ever be paid, he said.

Harnett's lawyer Rennie Gould appealed the decision to lift name suppression on Friday.

A psychiatric assessment revealed Harnett was "not the man he once was", Gould said.

He had cognitive impairment and severe memory loss brought on by heavy alcohol use, she said.

Harnett's 95-year-old mother deserved one more summer without the humiliation from her son's actions, she said.

Judge Joseph Williams dismissed the appeal on Friday because he did not think the mother's hardship warranted name suppression.