Half of all adult Australians were estimated to have bought a Powerball ticket desperately hoping to scoop the $100m on offer two weeks ago, but the person who actually won the lot has so far proved shy about coming forward.

All we know about the winner of the monster June 12 draw is that they bought their ticket at the Bondi Junction Newsagency and they were not a registered player — a decision that could end up proving costly.

The Lotto spokesperson Matt Hart said they were working behind the scenes to collate all the information they could about the ticket holder so they could claim their windfall.

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“We’re hoping they check their ticket and make contact with us as soon as possible to start the prize claim process,” he said.

Mr Hart said he still hadn’t lost hope of uniting the mountain of cash with its rightful owner.

“We’ve had division one winners come forward months and even years after the winning numbers were drawn to claim their prizes,” he said.

“In most cases, these winners have told us the winning ticket was hiding in plain sight the whole time – in their wallet or purse, in the car console or on the fridge door.”

Mr Hart said that, given the size of the prize, they were eager for the mystery player to get in touch and start enjoying their good fortune.

“In New South Wales, players have six years to claim their prize. After that time, the prize is gone. So, while there is plenty of time, the clock is ticking.

“While we’re working behind the scenes to collate all the information we can about this mystery winner so we can unite them with their prize, we’re hoping they check their ticket and make contact with us as soon as possible to start the prize claim process.

The ticket holder shares the title of Australia’s third-biggest lottery winner.

Last week, The Lott’s Khat McIntyre said the winner could already be basking in their good fortune if they had registered it to The Lott Members Club.

“It’s the question many Aussies have been asking during the past seven days: who won last week’s $100 million Powerball prize, and do they know they’ve won?” she said.

“By registering your in-store or online lottery entry to The Lott Members Club, not only are we able to contact you straight after the draw if you win big, but your prize is secure.

“Even if you happen to lose or damage your winning ticket, if it is registered to you, we could still unite you with your prize, providing the ultimate peace of mind.”

Joining is free and could turn out to be a multi-million-dollar decision.