It's not surprising at all that the press releases are written in advance of arrests. Preet Bharara, the US Attorney responsible for this, is a symbol of everything that is wrong with the US justice system. His every action is designed to maximize his PR and advance his political career. If on occasion he happens to perform his actual job in the process, that is only incidental. If you look closely you'll see that he actually has professionally applied makeup during his press conferences - these are manufactured dog and pony shows. He was looking for a case that would allow him to ride the PR coattails of Bitcoin, and he found one.
In my opinion, prosecutors like this are as despicable as many of the people they prosecute.