An appeal has been lodged by the lawyer of Jaden Lee Stroobant, who murdered and sexually violated his neighbour.
Stroobant, 21, was sentenced to life in prison with a minimum non-parole period of 17 years for murder and to preventive detention for the sexual attack at the High Court at Auckland on May 26.
He admitted killing 69-year-old Cun Xiu Tian in her Te Atatu home in January last year and violating her as she lay dying.
Defence lawyer Emma Priest told NZ Newswire she has filed an appeal against the "manifestly excessive" sentence of preventive detention which was imposed on the two counts of sexual violation.
"We've just started the process... the exact grounds are still being formulated," she said.
"In short, the imposition of preventive detention [for sexual violation] was out of line with all other cases and the exercise of discretion was wrong in this case.
"In particular, his age, guilty plea and that he had never been offered substantive rehabilitative opportunities as his longest previous sentence was six months imprisonment, will be key grounds."
Ms Priest said the sentence for murder is not being appealed.
Before Justice Graham Lang handed down the sentence in May, Ms Tian's son-in-law, Jianzhong Wang, told the court since the attack he had "experienced the darkest moments of my life".
At the time of the attack, Stroobant was still under prison release conditions following a burglary conviction.
Ms Priest said at the trial the attack was "out of character" compared to Stroobant's previous offending and that he had a dysfunctional childhood - including being expelled from school at 12, abused and spending time living on streets.
But Justice Graham Lang said an indefinite term would be an "incentive" for rehabilitation.
"It is the only realistic way the community can be protected," he told the court.