"Establishing how this firearm and the .22 came to be at the Pitangi Track property will assist us in piecing together activity in the lead up to Mr Hall's disappearance. It is quite possible that these firearms were used in the murder of Mr Hall so information about them could be critical."
Mr Hall, 47, was last seen around the end of May at his remote Pitangi Track lifestyle block, and after an intensive but fruitless search police are treating the case as a homicide.
Mr Hall's past was described by police as "chequered". He was paroled from prison in 2009 after serving a sentence of seven-and-a-half years for dealing "a variety of drugs", receiving and unlawfully possessing a pistol.
Yesterday, police said they had received sightings of a dark grey Nissan Terrano 4WD vehicle they believe could have been involved in his disappearance.
Police were canvassing the area of Scotts Ferry, near the mouth of the Rangitikei River southeast of Wanganui, in the hope of gathering more information about the 4WD.
Mr Kirby said the canvas had produced a number of sightings of the vehicle, which supported their belief it was linked to his disappearance. The vehicle was seen at Pitangi Track the weekend Mr Hall went missing.
Police were now considering carrying out a search in the area.
- NZPA