The longest non-parole periods imposed in New Zealand's legal history, in ranking order:
* Feb 2003 - William Bell, 25, jailed for a minimum non-parole period of 33 years for killing three people at the Mt Wellington-Panmure Returned Services Association on December 8, 2001.
* Dec 2002 - Bruce Thomas Howse, 40, 28 years non-parole on his life sentence for the murders of his stepdaughters Saliel Aplin and Olympia Jetson in their Masterton sleepout on December 4, 2001.
* April 2007 - Convicted double killer Graeme Burton given a sentence of preventive detention with a non-parole period of 26 years, after pleading guilty to all 11 charges arising from his rampage on Wainuiomata Hill in January, which left quad biker Karl Kuchenbecker dead and four others injured.
* Aug 1995 - Joseph Stephenson Thompson, 37, the south Auckland serial rapist, 25 years non-parole for the rape and sexual assault of women and girls over a 12-year period.
* July 1998 - Malcolm Rewa, non parole period of 22 years on his preventive detention sentence for a series of sex offences between 1987 and 1995. Rewa pleaded guilty to raping six women, but a jury later found him guilty of raping 13 others.
* June 2007 - Jason Reihana, 35, minimum non-parole period of 21 years for fatally stabbing his former partner, the mother of his two sons, and her new boyfriend in a fit of jealous rage.
* February 2008 - Michael John Curran, 28, who murdered two-year-old Aaliyah Morrissey while on bail for killing his girlfriend Natasha Hayden, 24. Sent back to jail for at least 20 years and six months.
* June 2006 - David Konia, 53, sentenced to a minimum of 20 years imprisonment for stabbing to death two elderly Feilding friends after they didn't shout him a drink.
* May 2005 - Antonie Dixon given life sentence with a 20-year, non-parole term for the murder of James Te Aute in Auckland and an enraged sword attack on Simonne Butler and Renee Gunbie at Pipiroa near Thames in January, 2003. In September this year the Court of Appeal quashed his convictions and ordered a retrial.
* Aug 2002 - Mark Lundy, 20 years non-parole on his life sentence for killing wife Christine and seven-year-old daughter Amber in August 2000.
* 1996 - John David Fleming sentenced to preventive detention with 20-year minimum non-parole. According to the Sensible Sentencing Trust offender database, Fleming - a former Sunday school supervisor - is the country's "worst known sex offender", having admitted 4229 sex offences relating to 42 boys aged four to 15.
* 1991 - David Ian Bach, Mt Maunganui painter, sentenced to preventive detention for 12 sex offences against young girls. Trust database recorded it as applying for at least 20 years.
* Oct 2006 - Anthony Paul Doyle, who blasted a couple to death with a shotgun under a bridge near Tauranga after a dispute over a drug debt, sentenced to life imprisonment with a minimum non-parole period of 19 years.
* Sept 2004 - Chinese student Wen Hui Cui, 23, found guilty of murdering his estranged girlfriend and one of her friends in Auckland in 2003, and jailed for a minimum of 19 years.
* May 2007 - Shane Randle, 28, sentenced to preventive detention and life imprisonment for the "depraved murder" and "sadistic" sexual violation of Wanganui barmaid Tania McKenzie on her 20th birthday. Minimum non-parole period of 19 years.
* Dec 2007 - Cui Xiangxin and Li Zheng, both 22, jailed for a minimum of 18-1/2 years for murdering fellow Chinese student Wan Biao whose body was found floating in a suitcase on Waitemata Harbour in April 2006.
* Dec 2006 - George Charlie Baker, 25, jailed for a minimum of 18 years for strangling and stomping Liam Ashley, 17, in the back of a prison van in August 2006.
* Aug 2006 - Peter Steven Waihape, 29, sentenced to a minimum of 18 years. He ran over a prostitute after engaging her for sex, then threw her bound body into the Avon River. Four days before, he abducted a 17-year-old, drove her around for two hours, sexually violated her and forced oral sex on her.
* Oct 2000 - Taffy Hotene, who killed Auckland journalist Kylie Jones, received an 18-year non-parole life sentence for murder, and preventive detention for raping her.
* Oct 2007 - Michael Scott Wallace, 46, sentenced to a minimum 18 years for murdering German backpacker Birgit Brauer, whose beaten and stabbed body was found in Lucy's Gully, near Oakura, southwest of New Plymouth in September 2005.
New sentencing and parole laws came into force in July 2002. Among the key changes:
* the minimum non-parole period for the worst murders, where specified aggravating factors are present, increased from 10 to 17 years;
* the worst offenders have to wait up to three years between parole applications instead of automatically applying each year;
* the abolition of automatic release at two thirds of a sentence for serious violent offenders;
* preventive detention available for a wider range of sexual and violent offending.