BERLIN — A giant gold coin that was stolen from a museum in the heart of Berlin this year was probably smashed or melted down and will most likely never be recovered, the authorities said on Wednesday, as they announced four arrests, including that of a museum security guard.

Early on the morning of March 27, burglars used a ladder to climb through a window from elevated railroad tracks outside the Bode Museum, famous for its collections of statues, coins, medals and Byzantine art. They “forcibly opened” the window, then “violently shattered” the bulletproof case surrounding the coin, according to a police spokesman, Winfrid Wenzel.

They carted their prize in a wheelbarrow to a car parked in Monbijou Park nearby, according to the police statement issued on Wednesday.

At a news conference on Wednesday, Mr. Wenzel added new details to a crime that has captured attention both in Germany and in Canada — where the coin, weighing about 221 pounds, was minted in 2007 — for its brazenness.