Kaylem Rayne Webb-Hirst (16) and Michael Shelford Mauheni (17), both of Oamaru, died when the vehicle in which they were passengers crashed and caught fire at the intersection of TY Duncan and Shortland Rds on June 12.
The 18-year-old driver, also from Oamaru, survived and spent several weeks in Dunedin Hospital, recovering from serious injuries sustained in the crash.
Detective Sergeant Hannah Booth, of Oamaru, said yesterday the investigation into the circumstances surrounding the crash was in its final stages, but would not say whether the driver would face charges.
''The file is going through our review process and once that has been completed we will know whether charges will be laid.''
She said the driver ''has been approached'' by police, but would not confirm if they had been formally interviewed.
Det Sgt Booth defended the length of time the investigation had taken, which she said was not unexpected given its complexity.
''I think it's the normal amount of time for an investigation like this. We just need to make sure that everybody is spoken to, all of the facts are identified, and there's a lot of factors to consider in an investigation like this. We just want to make sure we get it right for all of the families involved in this.''
