Queenstown police are still appealing for witnesses after a five-tonne digger and a car were damaged by fire early on Sunday.
Sergeant Steve Hindmarsh said police were called to the Kelvin Heights side of the Kawarau Falls bridge at 2.50am on Sunday after a report of a digger on fire.
Police and firefighters attended but about 15 minutes later were called to State Highway 6.3km south of Jacks Point, where a silver 1992 Nissan Primera, parked on the side of the road, was also on fire.
"They were very close to each other in proximity and very close to each other in time frame,'' Sgt Hindmarsh said.
Police believed the incidents were related and were treating them as arson.
Yesterday, Sergeant Brian Cameron said there were "some positive lines of inquiry''.
The digger, belonging to DownerEDI Works, formerly Works Infrastructure, was extensively damaged, as was the Nissan, which was possibly stolen.
Fire Investigators were at both scenes yesterday, but Sgt Hindmarsh said the cause of the fires had not been determined. Police are seeking witnesses.
Yesterday afternoon Downer-EDI Works Queenstown Lakes supervisor Michael Scott said the eight-year-old digger was being used for repairs on the Kawarau Falls bridge and had not been used since early Friday.
Works stop on the bridge overnight on Friday and Saturday. Mr Scott said last night was to have been the last to use the digger, but because of the fire, he spent most of yesterday trying to source another one.
The small digger, used primarily in road works and subdivisions, was a "write-off'', he said.
"A replacement value would be between $65,000 and $70,000.
"[The offenders] don't think of that sort of thing when they're having their fun.''
