Police have made a fresh appeal for information in relation to the 2008 death of Mellory Manning.
They're wanting to identify 'Male B', whose DNA profile was obtained from a semen sample located during a post-mortem examination.
Manning's body was found on the morning of December 19, 2008 floating in the Avon River, near Dallington Terrace, Christchurch.
The night before, Manning, a street worker, "is known to have had two clients" between 9:30pm and 10:35pm. Both clients have been identified and spoken to, police say, and the last known sighting of the woman was between about 10:35pm and 10:45pm on the corner of Manchester and Peterborugh St.
"Mel was in possession of her own cell phone and she sent a series of texts to one of her previous clients that night at about 10.43pm," Detective Inspector Greg Murton says. "The cell site data on that text indicates that she was on the move, likely in a vehicle, and had left her corner."
Following her death, Operation Dallington was launched and has been described by Det Insp Murton as "complex and challenging".
"It was clear that Mel was subjected to a prolonged and violent assault that caused her death.
"It is also the belief of the investigation team that due to the nature of her injuries, a number of persons were involved in her death."
Det Insp Murton says Mallory's known clients have been eliminated as being Male B.
"The investigation team was extremely hopeful at the time that the Male B DNA sample would be matched to someone on the criminal DNA database. Unfortunately, that was not the case.
"Considerable time and effort has been spent by the investigation team to obtain DNA samples from persons of interest over the last 13 years who were not on the criminal DNA database.
Unfortunately, we have not been able to identify Male B.
"Information is sought from members of the public who may have information as to the identity of Male B or have any other information as to who was involved in Mel’s death and what occurred that night."
These people are urged to come forward to "give the family some closure".
Manning is said to have been wearing a "distinctive pink skirt and a blue and white polka dot bikini top" at the time. She was described as being a "street-wise feisty young woman who knew all about the dangers of her business".
"Anyone who has any information which may assist is asked to call Police on 105 and quote Operation Dallington. Information can also be provided anonymously be ringing Crime Stoppers on 0800 555 111."
