Ngatai Lynette Manning, known as Mellory Manning and sometimes recorded as Mallory Manning, was 27 years old when she was killed in Christchurch, New Zealand, on 18 December 2008. Manning worked as a sex worker and was picked up from the Manchester Street area of central Christchurch. She was taken to a property in Avonside and killed by stabbing, strangulation, and assault with a metal pole. Her body was placed in the Avon River and recovered the following morning, 19 December 2008, after a jogger noticed it and a passing kayaker pulled it to the bank. Police identified Manning from her fingerprints.
Manning had a difficult upbringing, leaving school at 14 after time in foster care and beginning sex work at 15. In July 2008 her elder sister, Jasmine, died by suicide. Afterward, Manning stepped away from sex work, joined a methadone treatment programme, considered studying art, and planned to start a family with her partner. Financial hardship led her to return to street work for a single night in December 2008, during which she was killed.
Over roughly four years, investigators interviewed more than 900 people and obtained Manning's client list. Forensic work included DNA sampling and, in January 2009, the discovery of grass seeds on her cardigan that pointed to possible locations. In December 2010, police identified a Galbraith Avenue property in Avonside, described as a Mongrel Mob gathering place, as the suspected site of the killing. In September 2011, police confirmed that semen recovered from Manning's body did not match any of her clients from that night.
In March 2012, 24-year-old Mauha Huatahi Fawcett, a gang prospect who had fetal alcohol spectrum disorder, was arrested and charged with Manning's abduction and murder. He was interviewed eleven times; according to the account, detectives lied to him, discouraged him from consulting a lawyer, and pressured him into a confession. His trial began in February 2014, he represented himself, and in March 2014 a jury found him guilty. In May 2014 he was sentenced to life imprisonment with a minimum of 20 years.
In 2016, neuropsychologist Valerie McGinn diagnosed Fawcett with fetal alcohol spectrum disorder. On 7 August 2017, the Court of Appeal quashed his conviction and ordered a retrial, citing his self-representation defence and the undisclosed diagnosis. In September 2021, High Court Justice Rachel Dunningham ruled his statements inadmissible, and on 26 October 2021 the murder charge was dismissed. No other person has been charged. Contemporaneous coverage of the case appeared in New Zealand outlets including stuff.co.nz and tvnz.co.nz.