It followed the arrest of a 23-year-old Oamaru man, a 22-year-old Oamaru farmhand, who has interim name suppression, and 18-year-old Steven Kenneth Boskell from Palmerston.
A 52-year-old Oamaru woman has also been charged with being an accessory after the fact in relation to the murder.
Search teams of around 20 people, including seven specialist search staff from Christchurch, have today been continuing to scour an area of the Maheno-Kakanui Road for items of interest in the Operation Steelers investigation.
A number of items of interest have already been located by a team searching an area of about 500-600 metres along the road.
Police searchers have been joined by 14 local community volunteers from the North Otago Search and Rescue Club, the North Otago Tramping Club and the local fishing club.
"Their assistance is hugely appreciated and they've been fantastic in giving up their time to help police in their search for items of interest,'' said Detective Senior Sergeant John Ferguson.
The search is expected to be completed today.
A scene examination at Mr McFarlane's house was completed yesterday evening.