Detective Inspector Doug Brew of Palmerston North has been brought in to oversee the hunt for killers in Marton and Wanganui.
Mr Brew, crime services manager for the central police district, took up the "directional oversight" role for both homicide inquiries on Friday after returning from holiday.
Mona Morriss, 83,
was stabbed to death in her pensioner flat in Wellington Rd, Marton, on January 3 or 4.
She suffered multiple stab wounds in a brutal attack that included a sexual element, police say.
Her body was found by a family member on January 5.
Two days later, the naked body of Wanganui woman Tania McKenzie was found floating in the Whanganui River near Somme Parade.
Miss McKenzie, 20, died of serious head injuries.
Marton is 37km southeast of Wanganui.
There has been no evidence of any link between the murders, but police investigating each killing have shared information.
Mr Brew said he expected both cases to take some time to solve.
Detective Sergeant Mike Oxnam will continue to head the Wanganui inquiry, Operation Somme, and Detective Sergeant Tim Smith will head Operation Wellington in Marton.
In recent developments, Mr Smith said yesterday that the purse that Mrs Morriss used while paying for groceries during one of her last public outings is missing.
Both her flat and the surrounding area have been searched.
Mrs Morriss' flat was commercially cleaned on Tuesday and handed back to the family yesterday.
Meanwhile, in Wanganui, police were appealing for witnesses who saw a woman being chased about the time Miss McKenzie met her violent death.
Mr Oxnam also said police believed Miss McKenzie was in an area about 2km north from where her body was found between 2.55am and 10.30am on the morning she died.
- NZPA
