Detective Senior Sergeant Colin Blackie said it was believed the Dutchman was alone at the time of the accident and there was ''a suggestion'' from a witness, or witnesses, he was ''prone on the road'' when struck by the taxi.
''It's too early for me, with a number of witnesses still to be interviewed, to make that call about how he came to be on the road and in what position, what stance; whether he was prone or vertical.
''I'm just not going to say that yet until we've interviewed all the people, some who were direct witnesses, that we're still to locate and see,'' Det Snr Sgt Blackie said.
''We're keeping an open mind about what caused this tragedy, how this gentleman came to be in the position he was, and we're not apportioning blame to anyone yet.''
APNZ reported the crash happened just outside Ian Norman's house, at the intersection of Beacon Point and Eely Point Rds.
''I would say [the victim] was asleep on the road by the way we didn't hear anything,'' Mr Norman said.
''There's no real marks on the road. Obviously, the body wasn't thrown so maybe he was asleep.''
The location where the man was hit suggested he was walking with traffic rather than against it, he said.
Det Snr Sgt Blackie would not name the taxi company involved but said the driver was ''understandably shocked''.
''We're giving him some time and offering Victim Support to him as well as other key parties.''
The driver and his two passengers tried to help Mr van Rosmalen at the scene and called emergency services, Det Snr Sgt Blackie said.
''That's to their credit, that everyone that stopped did their best.''
Ken Hart, of KT Sightseeing and Taxi Wanaka, said a driver for his company had witnessed the accident but his company's taxi was not involved. The KT driver would not be speaking to media at this stage, Mr Hart said.
Hamish Fraser, from Wanaka taxi company Yello!, declined to comment.
Police appealed to the public for any further sightings of Mr van Rosmalen as he walked north from Wanaka township along Beacon Point Rd between 1am and 3.30am yesterday. He was wearing a red beanie, dark jacket/hoody, jeans and black Nike shoes.
Mr van Rosmalen's body has been transported to Dunedin, where a postmortem examination will be conducted this morning.
Anyone with information is asked to call the Wanaka police's Operation Beacon team on (03) 443-7272(03) 443-7272.