A homicide inquiry, involving more than 40 police and support staff, was launched two weeks ago after Justin Conrad McFarlane (35), of Elderslie, was found dead in his Pine Hill Rd home on September 11.
Since then four Oamaru men have been arrested and charged with murdering Mr McFarlane. Detective Senior Sergeant John Ferguson said the number of staff involved in the investigation had been cut to 19, and inquiries would continue for another month.
''We are currently continuing with background inquiries to determine the circumstances that led to Mr McFarlane's death. Inquiries are ongoing in relation to people who might have assisted those jointly charged with murder.''
Det Snr Sgt Ferguson said the investigation team were ''continually'' reviewing evidence.
The culpability of a fifth person was also still being assessed, he said.
Although he was unable to say how much the two-week operation, named Operation Steelers, had cost to date, it was a ''significant investigation in terms of the requirement to complete a large number of inquiries relating to multiple alleged offenders'', he said.
Steven Kenneth Boskell (18), of Palmerston, Ryan Warren Geary-Smart (23), of Oamaru, and two other 22-year-old men from Oamaru, both of whom have interim name suppression, have been charged jointly with the murder and have been remanded to appear in the High Court at Timaru on October 1.
A 26-year-old Oamaru woman and a 17-year-old Oamaru male have also both been charged as an accessory after the fact, in relation to assistance given to those now charged with murder, and are due to appear in the Oamaru District Court on October 9.
