Southern Police Acting Detective Inspector Colin Blackie yesterday said he was confident all suspects in the alleged murder of Mr McFarlane were now in custody, after a 22-year-old man was arrested on Monday night.
The man was arrested after he was located on a public bus travelling north from Dunedin to Oamaru late on Monday afternoon.
Acting Det Insp Blackie said police involved in the investigation were travelling South to Dunedin at the time and had previously received information which suggested the 22-year-old man and his girlfriend could be on the bus.
''The man was taken to Dunedin Central Police station for questioning and remanded in custody to appear in the Dunedin District Court.''
The man, who has interim name suppression, was dealt with by registrar's adjournment in the Dunedin District Court yesterday, charged jointly with Steven Kenneth Boskell (18), of Palmerston; Ryan Warren Geary-Smart (23), forest worker, of Oamaru; and a 22-year-old Oamaru farm hand, who also has interim name suppression, with murdering Justin Conrad McFarlane.
The latest arrest means four people aged between 18 and 23 have now been charged with the murder of 35-year-old Mr McFarlane, who was found dead in his Pine Hill Rd house in Elderslie on Wednesday.
All four have been remanded in the custody of the Timaru High Court until October 1.
Acting Det Insp Blackie was confident all of the people involved in the alleged murder of Mr McFarlane had been located and arrested, although the ''potential'' involvement of a fifth person was still being assessed.
Police were still speaking to that person, he said.
He said the inquiry, named ''Operation Steelers'', had received ''good information'' from most of the general public in North Otago, but added he was ''disappointed'' some people may have aided the suspects since the investigation began on Thursday.
''We are very grateful for the assistance from the community in Waitaki. However, it's also been disappointing that a number of people appear to have been assisting those now facing murder charges either to evade police or to destroy evidence that might be crucial to the case.
''These people that have put themselves in a position now where we are going to investigate them have done themselves a disservice, and the community, and the taxpayer, for the costs this investigation is incurring.''
He warned that anyone found to have aided or protected the four men would also be the subject of further inquiries.
''To that end a second phase of this investigation has been directed by me to hold those persons to account, where we will be investigating their culpability and, if necessary, placing them before the court.
''There was one person, since arrested ... and charged with murder, that was located coming out of a boot of a vehicle and, therefore, the occupants of that vehicle are clearly of interest to us, about how they have assisted in that person avoiding this investigation and detection.''
A 52-year-old Oamaru woman, who was known to some of those charged with the murder, would appear in the Dunedin District Court later this week charged with being an accessory after the fact to the murder of Mr McFarlane.
At present, police were ''potentially'' looking at investigating another eight people, he said.
''This is a clear message that needs to be sent to the community. This was a tragic death of a person and why would anyone want to aid and abet anyone avoid detection or arrest?''
