Every last person involved, regardless of who they are. They All belong in prison in MEXICO for whatever life they have left. By the way nothing at all prevents the DA in the affected counties from FILING CHARGES except politics of course. File Murder Charges against all of them, have the Governor sign the warrant and demand extradition to answer the charges, FORCE Obama to issue Pardons it will end his career immediately.
That is called an Ace in the Hole and should never be revealed in the opening play or first round of betting.
And a powerful ace it is.
The POTUS can only pardon FEDERAL crimes. If the state(s) want to file charges for murder, conspiracy, etc., they could file those charges and BHO could not pardon them, because they are state charges - not federal ones.