Forensic scientists have made "some progress" towards identifying the object which struck and killed motorist Rutger Hale near Lake Hawea seven weeks ago, police say.
Detective Sergeant Brian Cameron, of Queenstown, said yesterday recent scientific testing on parts of Mr Hale's car had advanced the investigation.
He declined to elaborate.
"There has been some progress, but nothing definitive so there's going to be further testing ... it will depend very much on the availability of both experts and equipment as to whether that occurs prior to Christmas."
Mr Hale, 22, died early on October 24 when an unknown object flew through the windscreen of his car and hit him in the head as he drove between Lake Hawea and Wanaka.
The object was not found.
Last month, sections of the car's interior were sent to the physical evidence team at the Institute of Environmental Science and Research (ESR) in Auckland for examination.
Det Sgt Cameron said police still hoped to be able to identify what caused Mr Hale's fatal injury and were actively working on the investigation.
"Don't think that the inquiry has stalled . . . one of the things that we're looking at is the registered owners of white utility vehicles in the central lakes area."
Mr Hale's partner, Danielle Oylear, 26, who was in the passenger seat when the object passed through the car, reported seeing a white utility travelling in the opposite direction at the time.
Police still want to speak to drivers of vehicles in the area when the accident happened, including the driver of a vehicle towing a boat. That driver pulled over at the top of Maungawera Hill to let a white utility past, and has yet to come forward.