The Fields Medal is the most prestigious award in mathematics, a recognition so esteemed that it is often compared to the Nobel Prize.

Every four years, a selection committee chooses two to four mathematicians under the age of 40 to honor for their “existing work and for the promise of future achievement.” Then, at a meeting of the International Congress of Mathematicians, they announce the winners and hand out 14-karat gold medals that cost more than $4,000 each.

When Caucher Birkar, a professor at Cambridge University, heard that he would be awarded one of this year's medals at a ceremony Wednesday in Rio de Janeiro, he was thrilled. Birkar, who specializes in algebraic geometry, was raised in a Kurdish village in Iran and, after studying at the University of Tehran, sought political asylum in Britain and completed his studies at the University of Nottingham.

In an interview with Quanta Magazine, Birkar said that “to go from the point that I didn't imagine meeting these people to the point where someday I hold a medal myself — I just couldn't imagine that this would come true.”

Then the medal was stolen from him.

The recognition is huge, but the award itself is quite small: The medal is only 2½ inches wide. Birkar apparently put his medal in his briefcase, alongside his wallet and phone. He left the briefcase on a table in the convention center, and in a matter of minutes, the briefcase was gone, according to Brazilian outlets.

Security officers later found it, but the wallet and the medal were missing. In a statement, the organizing committee said that it is “cooperating with local police authorities in their investigation” and that “images recorded at the event are being analyzed.”

Cambridge University released a statement saying that Birkar was honored “for his work on categorizing different kinds of polynomial equations.”

“He proved that the infinite variety of such equations can be split into a finite number of classifications, a major breakthrough in the field of bi-rational geometry,” the statement said.

The award also comes with a cash prize of about $11,500. This is the first time that Brazil has hosted the International Congress of Mathematicians. Brazilian mathematician Artur Avila won the award in 2014, the first time that Brazil had taken home the prize.

The other Fields winners this year are Peter Scholze, a professor at the University of Bonn; Alessio Figalli of the Swiss Federal Institute of Technology in Zurich; and Akshay Venkatesh, from Princeton and Stanford.

Birkar recognizes that his rise to mathematical fame was particularly improbable, having grown up during the 1980-1988 war between Iran and Iraq.

“War-ridden Kurdistan was an unlikely place for a kid to develop an interest in mathematics,” he said at the conference in Brazil. “I'm hoping that this news will put a smile on the faces of those 40 million people.”