Update to Gold Coin Current Event: Stolen??

Article: Last week, we did a current event about a California couple finding gold coins. [Ask kids to recall the story.] Well, there's an update: It turns out that the couple may not be lucky after all. The buried gold coins, valued at $10 million, may actually have been stolen from the US Government (The Mint) in 1900! According to a local newspaper, two facts about the coins -- their literal value of $27,000 and that they are mostly uncirculated coins in perfect condition, match the two details from a gold heist in 1900 from the San Francisco Mint! In particular, there is one coin in the mix that is extremely rare because it is a $20 gold piece without the words "In God We Trust" on it. Such a coin only existed at the SF Mint and never left it until the robbery. If this is all true, the couple would likely get a "finder's fee," but would have to return the coins.

Questions:

• If this is true, who do the coins belong to and why? Why don't they belong to the couple? 
• What will the US Government have to prove to get the coins back? 
• Why does it matter that one of the coins is missing the words "In God We Trust?" 
• What does "uncirculated" mean? Why is this a significant fact?