Police say a car stolen on Saturday night was found down a bank where the large fires are thought to have started.
The vegetation fires started around 4.30am on Sunday and covered about 270 hectares of land near Porters Pass.
Police believed the vehicle was taken from a rural Bankside property and was involved in the theft of an ATM in Darfield around 3am on Sunday.
The ATM was pried off a wall and later dumped on Cridges Rd in the town, although no money was stolen.
The car, a Nissan Mistral, was found near Porters Pass Rd on Monday and Police said it was within the area where the fires were believed to have ignited.
It was found considerably burnt, Fire Area Commander Colin Russell said.
Russell said there was danger to public using the road while the fire was raging, with high numbers of skiers driving to Porters Ski Area.
He said there were also trampers in the hills on Sunday which were located by Fire and Emergency and made safe.
Russell also said any fire like this would cause environmental damage, and that ecosystems in the area may have been affected.
On Sunday, 10 helicopters with monsoon buckets were used to stop the fire from spreading further, and on Monday about 50 firefighters were sent to extinguish hot spots where it could flare up again.
Russell said high humidity and low temperatures overnight helped to keep the blaze under control.
State Highway 73 was closed on Sunday after the fire started near then crossed the road. It was reopened on Monday with one lane, with access restricted due to Fire and Emergency work on the blaze.
Christchurch Police urge anyone who knows anything about the two events to call them on 03 363 7400, or anonymously through Crimestoppers on 0800 555 111.