One of the men involved in the brutal attack on Rotorua businessman Peter Bentley has failed in a bid to serve his sentence at home.

The decision brought relief for Mr Bentley and his wife, Maggie.

"It's the best we could have hoped for, given his minimal sentence," Mr Bentley said.

In May, Desmond Mahanga Eru, 23, was sentenced in the Rotorua District Court to 23 months' jail after pleading guilty to burglary and being an accessory after the fact of an aggravated robbery of the Bentley's rural home.

Judge Phillip Cooper granted Eru leave to apply for home detention, but the Parole Board refused his application, saying he was a risk to the safety of the community.

The Bentleys were at the Parole Board hearing in Taupo, and Mr Bentley was told of its decision this week.

Judge Cooper said Eru played a lesser role in the offending, but the Bentleys said he was the "instigator".

Eru had worked for the couple, and if it had not been for him, his three co-offenders - Mano James Tamati, Ronald Dean Hira and Hobson Epiha - would not have known who the Bentleys were or where they lived.

Tamati and Epiha, who committed the aggravated robbery, were sentenced to prison terms of 10 years and nine years respectively.

Hira was sentenced to two years and four months' for the burglary of the Bentley's home.

In its decision the Parole Board said Eru wanted home detention so he could get on with his life, his work and family responsibilities.

Eru told the board he was coerced under a threat of violence into the offending by his co-offenders, who were cousins - a comment which surprised the Parole Board.

Board members said they doubted Eru's level of remorse, and felt he was not being truthful and had minimised his involvement.

The board's decision has in some ways ended the Bentley's ordeal, but they say there will never be closure.

"The people involved in this have destroyed a lifestyle we had," Mr Bentley said.

He said he would work with the Sensible Sentencing Trust in its effort to increase sentences for serious crimes. He hopes to encourage others to become involved.

"We want the taxpayers of New Zealand to know they can contribute to change if there is enough of them and they speak loudly enough."