The driver who crashed an illegally modified car, killing a Mosgiel brother and sister, has been charged with manslaughter.
The 20-year-old Milton man faces two charges of manslaughter over the deaths of siblings Shannon (22) and Danielle (17) Kiriau and a further two charges of dangerous driving causing injury to the car's other occupants.
The charges come five months after his Honda Integra crashed on the Southern Motorway early on May 18.
Shannon and Danielle died at the scene, while teenagers Courtney Donald and Caitlin Adams were injured.
Miss Donald (17 at the time of the crash) remains in Dunedin Hospital because of her injuries.
Inspector Mel Aitken said the complexity of the investigation meant it was some time before charges were laid.
''Serious investigations such as this are complex in nature and time-consuming, but the time taken is necessary to ensure all evidence is considered and the appropriate action is taken,'' she said.
The driver was summonsed to appear in the Dunedin District Court on November 18, Insp Aitken said.
He speculated online earlier this month about his chances of imprisonment.
He was told by his lawyer he could be imprisoned ''anywhere between 3-6 years'', a post attributed to him on a social media website said.
''[At] the end of the day lives were lost and I was operating the motor vehicle. Car fault, road fault or my fault, I'd still be getting charged,'' the post read.
The driver was on a learner's licence at the time of the crash, and had swapped a van for the Integra just days before.
The car had not passed a warrant of fitness since early 2012.
In May, police estimated the car, at the time of the crash, was travelling at 180kmh based on skid-mark analysis.
The Integra allegedly spun several times before hitting a light pole and then a tree.
The driver is understood to have since lost his licence and regained it.
The reason for the loss of licence is not known, but regulations provide that if a driver accumulates 100 or more demerit points in any two-year period, their licence can be suspended for three months.
