A truck driver involved in a fatal crash in Manawatu last week has still not been interviewed by police due to the severe shock he suffered over the incident.
A mother and son died in the three-vehicle crash on State Highway 1, near Sanson and Foxton, last Wednesday.
The crash involved two large trucks and a car, and occurred just after midnight.
Central Police District communications manager Sara Stavropoulos said no charges had yet been laid over the crash.
"We haven't formally spoken to one of the truck drivers yet. Once that's been done, and the ball's rolling on that...then we'll obviously look at potential charges.''
"Both of them were obviously taken to hospital to be checked out. Neither of them sustained any injuries, but after an event like that some people are in a substantial amount of shock so you can't really talk to them.''
Margaret Jane Turnbull, 51, and her son, Trent Whitburn, 20, were in the car and died in the crash and fire that followed.
A truck owned by chilled food transport company Big Chill and the car had been cleared of any culpability by police.
The investigation into the crash was ongoing, and police had reviewed CCTV footage from the Big Chill truck, Ms Stavropoulos said.
The yet to be interviewed driver was driving a truck owned by Freight Lines, which was travelling behind the car.
Freight Lines chief executive Barry Raymond said they were assisting police and the New Zealand Transport Authority with their investigations.
Freight Lines would also be launching its own investigation, he said.
The driver involved in the crash was from Hamilton and had driven for Freight Lines through a contracting company for the past seven years.
"It's just a tragic loss of life,'' Mr Raymond said.