Police arrested four men today on suspicion of stealing a 100kg solid gold coin the size of a vehicle tyre from a Berlin museum.
Regarded as the world's largest gold coin, it was stolen from Berlin's Bode Museum.
The Canadian coin with the picture of Queen Elizabeth II has a face value of 1 million US dollars.
The raids of 13 different buildings lasted several hours, but the gold coin was not recovered.
Criminal investigator Carsten Pfohl said: "We are assuming that the coin was in part or in whole sold off".
The coin, with a diameter of 53 centimetres and 3 centimetres thick and weighing 100 kilograms (221 pounds), has a face value of $1 million, but given the high purity of gold used in the coin, its melt down value is estimated at around $4 million (£3,112,800).
He said searches of the apartments were still continuing, but so far the coin hadn't been found. Experts think the coin may have been melted down to cash in on the gold, Wenzel added. The authorities also searched a neighborhood jewelry store that might have been involved in selling the gold.
Investigators believe the thiefs used a ladder and a wheelbarrow to remove the coin from the museum.
The two unidentified suspects were arrested in Berlin's Neukolln district. The police also found the rope, the ladder and the wheelbarrow as well a burning Mercedes in an underground vehicle park. After several interested buyers came forward, the Mint decided to make a very limited number of coins available for sale.
Police were unable to provide information about the whereabouts of the coin.
While one side of these coins features a hand-polished maple leaf design by Royal Canadian Mint artist and engraver Stan Witten, the other bears the effigy of Queen Elizabeth II by celebrated Canadian portrait artist Susanna Blunt.
In July, police published still photos made from surveillance video asking the public for help in finding the thieves who had stolen the coin from the museum.