This is a whole lot of wealth in the hands of US Marshal Services. A massive opportunity for the armed forces to generate significant income. The money that will come from this auction will be put to proper use.. purchasing armed officers' supplies like uniforms, police vehicles. And also funding some of the activities of the armed forces like charity events.
These coins must have been confiscated while facilitating crime.. they ended up being sued by the government in a civil law suit. And since the state laws can't protect people who are sued, the government doesn't have hard time in proving that the coins were used in crime. And this is how the US Marshal services could have claimed for the coins hence auctioning them.