23-year-old Gary Tweddle, originally from Reading, has gone missing in Australia's Blue Mountains.
He had been staying in Australia near Sydney for a work conference.
New South Wales Police say the search has now been wound down.
Gary's father David from Berkshire was helping searchers in Australia but says he still does not know what happened to his son.
More top news
Dry with clear spells overnight. Dry and breezy with sunny spells for much of tomorrow. Rain arriving later. Becoming humid from Monday.
Showers fading away with clear spells overnight. Dry with sunny spells for much of tomorrow with rain arriving later. Becoming humid later.
Feeling warm in this afternoon's sunshine. Breezy at times with the risk of an isolated shower.