KEY POINTS:
Police are stepping up efforts to try to identify a woman whose body was discovered weighed down in a river southwest of Auckland.
Two kayakers found the woman's body, wrapped in blankets and tied to a rock, was discovered trapped under a tree in the Wairoa River, near Clevedon, on Sunday afternoon.
Twenty extra police officers are now investigating the woman's death.
Hers is one of three homicides being investigated in the North Island after bodies were also found in Taupo and Napier over the last week.
So far this year police have also arrested a man for the murder of Bronwyn Whakaneke, found dead at a Mongrel Mob head quarters on January 8 and Clayton Robert Weatherston for the murder of Sophie Elliott, found dead after being attacked in her Dunedin family home on January 9.
A couple have also appeared in court charged with the murder of Michael Hutching, found wrapped in a mattress cover weighed down in the Clutha River on January 12.
Police have said an autopsy has shown the woman found in the Wairoa River was likely to have been in the water for a week.
The woman is believed to be between 30 and 50, of small build - about 45-50kg - and 155cm tall.
She was wearing adult incontinence pads and a dark T-shirt with stripes around the neck and sleeves.
Napier police are investigating the death of 46 year-old Chattrice Carroll-Poipoi found stabbed in her home on Monday.
Detective Senior Sergeant Bill Gregory said police are piecing together the woman's last movements. Twenty police officers have been called on to the case.
Mr Gregory said a weapon has been found at the scene and are appealing to the public for help.
"Someone may have noticed something untoward that they may think is irrelevant, but we would like to hear about it," Mr Gregory said.
Scottish tourist Karen Aim died on Thursday after being found in a pool of blood near Taupo Nui-a-Tia College.
Earlier this week a criminal profiling unit arrived in Taupo from Auckland. The unit has been asked to provide clues on a motive and identify any other lines of inquiry. Fifty extra police have been brought in to help on the investigation so far.
Investigation head Detective Senior Sergeant Greg Turner has renewed his call for vandals responsible for damage at Taupo Nui-a-Tia College to come forward. Police believe the damage at the college was done just before Ms Aim was found.
Police have previously said they are looking at links between the vandalism and the attack on Ms Aim.
Meanwhile police have said the woman who was found dead in Papamoa had died of natural causes. Initially police had been treating the death as suspicious.
In January 2007 there were seven murders, four in January 2006 and five in January 2005. So far this month there have been six.
