But Lars Berglund from Stockholm police's traffic unit, who has been leading the crash investigation, said the conclusive forensic report would not be available for another couple of weeks.
"There's no clear evidence that suggest intoxication, but that's not final. (...) It's impossible at this stage to rule out that the driver was under the influence," he told the Dagens Nyheter newspaper.
All four members of British indie band Viola Beach and their manager died when a car broke through two barriers and plummeted 25 metres from a canal bridge at Södertälje south of Stockholm on February 13th.
It has not been made public who was driving the vehicle at the time of the crash.
The bridge where the crash happened. Photo: Johan Nilsson/TT
Sjöfartsverket – Sweden's maritime authorities – has previously suggested the car hit the barriers at around 2am, when the bridge had been raised one-and-a-half to two metres to allow an oil tanker to pass underneath.
Berglund said he did not believe that the vessel, which likely ended up sailing right above the wreckage on its way to Södertälje, had contributed to the damages to the car or the band members' fatal injuries.
"We have not been able to work out how fast the car was travelling, but there were no traces like scraped paint from the ship on the car, so the causes of death probably had to do with the large forces involved when a car hits the water surface from such a height. All bodies were found in connection to the vehicle," he said.
Story continues below…
In an interview with The Local, Swedish traffic authorities last week debunked rumours that warning lights on the bridge had been faulty at the time of the accident.
Berglund added on Thursday that his team had also ruled out the possibility that the driver had been dozing.
"We have been able to see that the car braked before reaching the bridge. That allows us to rule out that the driver fell asleep. But what has actually happened is completely inexplicable. Right now there is no hypothesis," he told the Aftonbladet tabloid.