A $14.4 million winning lottery ticket in Iowa expires at 4 p.m. Thursday. In an effort to jog the memory of the winner or winners, the lottery has issued repeated reminders and even put up a countdown clock at its headquarters.

The winning ticket holder of a lottery jackpot turned up with less than two hours to spare before the prize expired, but the mystery surrounding the winner remains.

The $14.4 million winning lottery ticket in Iowa would have expired at 4 p.m. Thursday, one year after it was drawn.

The Hot Lotto ticket was purchased in Des Moines, Iowa, but the lottery has not revealed the date or time of sale. That information will be used to help verify the winning ticket, which was presented to the lottery by a lawyer on behalf of a trust.

The prize money will not be paid out until the lottery meets with the "actual winners" and the security questions about the purchase of the ticket are answered, the Iowa Lottery said in a release.

Lawyers with Davis, Brown, Koehn, Shore & Roberts contacted the lottery Dec. 27 about the prize on behalf of Hexam Investment Trusts, and brought the ticket to the lottery's office Thursday afternoon, just before the 4 p.m. deadline.

"We look forward to learning the details we've all been wondering about these many months, such as: How did the winner find out he had the jackpot-winning ticket? How long has he known he'd won? Why did he wait until the last day to turn in the ticket? Every winner's situation is different, and it's always fun to hear the story," Iowa Lottery CEO Terry Rick said Thursday.

The amount of the jackpot was originally estimated to be $16.5 million on the day of the draw - Dec. 29, 2010 - based on the cash from ticket sales plus interest if the winnings were to be paid out annually, as some winners choose.

Lottery officials said the value of the jackpot remains unchanged a year later, at $10.75 million, but the current low interest rates put the "annuitized" amount at $14.4 million.

The Iowa jackpot was not the only lottery prize to reach its expiry date this week: On Monday, a $77 million Powerball ticket expired Monday in Georgia.