As I understand it the charges against Weldon are the same as they were two years ago but couldn't be proven at that time. Now, the justice dept has a witness or two, so they asked the FBI to put it all together and build their case.
There's no doubt the timing of this information being leaked looks political.
Maybe the FBI leaked it, after they were set up, to spook Weldon/daughter/Sexton into trying to cover up, thereby revealing more or make the charges more serious?