I’m not sure this would be the case. If a prosecutor files a murder charge and accuses the defendant of shooting someone, does he have to re-file the case if it turns out the cause of death was blunt force trauma but it was still caused by the same perpetrator?
No, this is a different charge.
This is more like filing burglary charges, then finding out a murder had taken place in the store.
You cannot piggyback one charge on an existing one.
In your example it is the same CHARGE, just a difference in method.
Good point - if this process was consistent with reason and logic. And Constitutional law. But, as we know, it’s purely political. The “prosecutors” aren’t even pretending to adhere to any of the usual safeguards or protocols of a criminal court case. The jurors aren’t impartial; they’re a group of politicians. But, again, your point is well taken.
Once a D.A. has filed charges against someone, they can amend those charges as the evidence allows. They don't need to go back to a Grand Jury to get additional indictments.
That is not true of the House Managers. They are there only to prosecute the Articles of Impeachment passed by the house. They can't willy-nilly add additional scope to the chagres on their own volition.