The investigation is focussing on establishing the recent movements of Mr McFarlane and the events leading up to his death, as well as interviewing a number of people with connections to him, police said.
Yesterday afternoon, police executed search warrants at two homes in Oamaru.
During the searches - which the Armed Offenders Squad helped with - police uncovered a number of items of interest to the investigation. These are being forensically examined, said Acting Detective Inspector Colin Blackie.
Police said they still want talk with a number of people who either know about circumstances surrounding Mr McFarlane's death or who appear to have been involved in some way.
A forensic examination of the silver Nissan Skyline car thought to be linked to Mr McFarlane's death and the scene examination at Mr McFarlane's house in Pine Hill Road are continuing today.
Police will not release post mortem examination results until they have been confirmed by a pathologist.
About 40 police staff are working on the inquiry.