Police on Wednesday arrested four suspects aged between 18 and 20 over the theft of the valuable coin, snatched from Berlin's Bode Museum on Museum Island in late March.
Investigators believe the thieves wanted to melt down the giant "Big Maple Leaf" commemorative coin - issued by the Royal Canadian Mint in 2007- in order to make it into smaller portions of gold. The coin features a portrait of Queen Elizabeth II, and the museum gave the face value of the coin at €920,000, though the market price of 100 kg of gold is around €3.7 million.
According to Berlin-based newspaper Tagesspiegel, one of the men arrested was working as a security guard at the museum, and only started in March. He was also already known to police for license plate theft and not paying for car petrol.
Berlin police say they believe the massive coin was likely sold off, perhaps in pieces.
“We are assuming that the coin was in part or in whole sold off,” said criminal investigator Carsten Pfohl.
“I unfortunately have relatively little hope that we will find the coin, even in pieces.”
Pfohl added that they could still find traces of the gold rubbing off on things like clothes and cars.
Public prosecutor Martina Lamb said that the crime appeared to be the work of an organized gang, and that the suspects come from a known crime family. Investigators are also looking into nine other people connected to the family.
Tagesspiegel reports that the members of the family have been implicated in other crimes in the past, including dealing stolen jewellery, and stealing non-ferrous metal.
Special police forces raided and searched several apartments in the Neukölln district on Wednesday morning, and also seized a car. Tagesspiegel reports that police also searched an Arabic jewellery shop, and amid searches seized four guns as well as a lump sum of money in the six figure-range.
Surveillance video released earlier this month shows three people dressed in black, covering their faces as they walk along the platform of the Hackescher Markt S-Bahn station in central Berlin.
Police said that two of those arrested could be seen in the video, and neither of them had prior convictions.