Police have identified the store where a group of teenagers obtained 16 canisters of butane which killed a Riccarton High School student last month.
CCTV footage was obtained from stores in the wider Riccarton and Upper Riccarton areas which sold butane after Poihaere Eru, 17, died after inhaling - known as huffing - butane gas in Hansons Reserve.
She was with two other teenagers aged 14 and 16.
Detective Sergeant Craig Farrant declined to say what store the butane was from.
It is not illegal to sell it to teenagers but the information gathered would be given to the coroner who will hold an inquest into Miss Eru's death.
It is possible the coroner will make comment and possible recommendations at the inquest over the issue of teenagers accessing butane.
Miss Eru died after she and her friends were huffing butane gas in flax bushes.
Chief Coroner Judge Neil MacLean will release a report into butane inhalation deaths tomorrow.