Los Angeles: The heartbroken family of Australian tourist Lucas Fowler, who was shot dead alongside his girlfriend in a remote part of Canada, has arrived in the country as local authorities vow to look at all leads to solve the deaths.

Mr Fowler, 23, from Sydney, and his girlfriend Chynna Deese, 24, from North Carolina, were found dead on the side of the Alaska Highway last Monday after their blue 1986 Chevrolet van broke down.

Lucas Fowler and his American partner who were both found dead by the side of the Alaska Highway.

His father, NSW Police chief inspector Stephen Fowler told Nine News while transiting at Los Angeles airport that Lucas was "just a wonderful boy".

"He's a loss to so many people. And his girlfriend also - it's just devastating. And our heart goes out to the whole of her family," he said.