Well, she did say that Mr Crouch and his son are antagonists.

And she said what I suppose we must have known at the time, though I confess I'd forgotten: Barty Crouch arranged his father's release after the Ministry fell only to keep him under virtual house arrest for years. Let him out to work, but in a place so reduced from his former status it must have been a bitter punishment.

Certainly this trial was a hopeless task.

Perhaps he was mounting a significant rebellion, presenting evidence they meant to have quashed. (The business about Malfoy's abusive treatment of the brother.)

If so, it really is a wonder Mr Crouch hasn't been arrested himself.