Berlin (CNN) The trial has begun in Berlin of four men accused of stealing a huge, commemorative gold coin worth an estimated €3.75 million ($4.31 million) in an old-school heist.

"Big Maple Leaf," which has a diameter of 21 inches, is thought to be the second-largest gold coin in the world, according to the AFP news agency.

The coin, which features a portrait of the UK's Queen Elizabeth II, was minted in 2007 by the Royal Canadian Mint.

The suspects, one of whom is shown here, went on trial on January 10.

At the time of the theft on March 27, 2017, the coin was part of an exhibition at the Berlin Bode Museum. The defendants broke in through a window, press spokeswoman Lisa Jani of the Berlin Regional Court, where the trial is taking place, told CNN.

Three co-defendants, Wissam R., Ahmed R. and Wayci R., are accused of breaking in using information passed on by another defendant, Dennis W., a former security guard at the museum, said Jani.

Read More