The Fields Medal of a Cambridge University professor was stolen just half an hour after he was awarded the prize in Brazil’s Rio de Janeiro on Wednesday. Caucher Birkar was one of the four winners of the Fields Medal, often regarded as the Nobel Prize for mathematics. Indian-origin Australian mathematician Akshay Venkatesh was among the winners.

Birkar had reportedly left the 14-carat gold medal along with his wallet and phone in a briefcase on a table at the convention centre where the International Congress of Mathematics was taking place, according to BBC. The event’s security team later found the briefcase under a bench, but the medal was missing.

“Images recorded at the event are being analysed,” The Guardian reported, quoting organisers of the event. “The organising committee is cooperating with local police authorities in their investigation.”

Birkar was born in Iran and moved to the United Kingdom as a refugee two decades ago.

The Fields Medals are awarded every four years to the most promising mathematicians under the age of 40. Each winner receives a cash prize of 15,000 Canadian dollars (Rs 7.88 lakh).