The heirs to a renowned Philadelphia jeweler are locked in a court battle with the US government over the ownership of 10 rare gold coins from 1933 worth an estimated $75 million.

The government contends the coins were stolen because the 1933 Double Eagles, worth $20 when they were minted, were never authorized for circulation.

But lawyers for the descendants of Israel Switt, say that nobody knows exactly how their father came to possess the coins.

Since the government cannot prove they are stolen, it has no right to seize them.

The trial before US District Judge Legrome Davis began Thursday, and is expected to last two weeks.

Court documents filed in the case include tales of international intrigue, US economic history, and as the jury heard Friday, the minutiae of the accounting procedures at the US Mint over seven decades ago.

The case has captivated the world of coin collectors because the 1933 Double Eagles shouldn't exist. They were minted on March 15, 1933, more than a week after President Franklin Roosevelt, in response to a bank panic, ordered the US Treasury to halt the release of all gold.

The 1933 Double Eagles were never released, and in 1937, the Treasury destroyed all of the country's gold coins, melting them into gold bars and storing them in Ft. Knox as part of an effort to take the United States off of the gold standard.

David Tripp, the government's chief witness in the case and the former head of the coin department at the auction house Sotheby's, said Friday that just two of the 1933 Double Eagles, part of the official US coin collection at the Smithsonian Institution, were known to have survived the destruction.

But 10 of the coins surfaced in the 1940's. Over the next decade, the US Secret Service tracked down nine of them and destroyed them.

All of the owners said they bought them from Switt, or from someone who bought them from Switt, according to court documents.

The tenth entered the personal collection of Egypt's King Farouk in the 1940's, who received permission from the US government to ship the coin overseas.

In 1954, the coin turned up at an auction in Cairo, during a sale of the deposed king's coin collection. Upon learning of the 1933 Double Eagle, the US government requested that it not be sold.

The coin disappeared, only to turn up in the 1990s in the possession of British collector Stephen Fenton, who was arrested in New York City after trying to sell the coin to undercover US Secret Service agents.

The government and Fenton later consented to its sale at auction for $7.59 million and split the proceeds with the owner.

With that, the government believed that no other 1933 Double Eagles existed. But in 2004, Switt's daughter, Joan Langbord, told officials at the US Treasury that she had found 10 more 1933 Double Eagles in a safe deposit box.

The government seized them, leading to the court battle.

In sometimes grueling and highly technical testimony Friday, Tripp, who authored a book on the 1933 Double Eagles, said that the US Mint kept highly detailed records, not only detailing the number of coins it held in its vaults, but the years they were minted.

Since coins were not reported stolen, Tripp theorizes in court documents that an employee of the Mint somehow stole them and sold them to Switt.

Lawyers for Langbord and her two sons Roy and David, argue in court documents that having a theory as to how the coins left the mint isn't enough. The government must prove the coins were stolen. They argue that in the 1930s, it was common and even permissible for employees of the mint to replace old coins with new ones of equal value.