That is a weird quote. Is it normal for articles mentioning past trials to say "if a mistrial is declared, the trial was invalid"? Seems like an out of place, almost tautological piece of information. Maybe if something like a motion for a mistrial was filed, but why state a fact like that just randomly? It only serves to apply doubt to the validity of the trial outcome, with no apparent basis (I don't really know anything about the trial myself).