I don't know what evidence they had prior, but it looks like he indeed had classified docs.
IMHO, Trump is playing them. He's getting a huge boost in the polls after the FBI raid. We were warned this is how Trump could/would operate. Unfortunately, it's now the job of the political left and law enforcement to hold Trump accountable, when IMHO this should be the job of his political party.
We're in really sad shape. One party trots out Biden to lead us and the other party is afraid to stand up to Trump and their fringe supporters.