I've known Jim Fisher for, well, put it this way, my hair was brown when I met him, and he HAD hair. He and I were frequent sparring partners in the Fairfax County General District Court, when he was a fresh-faced deputy-under-assistant-Commonwealth's Attorney in the Bob Horan School of Jurisprudence. He's one of the best Commonwealth's Attorneys in Virginia, I think, and a recently elected one, having been recently associated with Jim Plowman's office in Leesburg. He's intellectually honest, fair-minded, and a decent person, despite his experience in Fairfax.
On the other hand, he does represent the Commonwealth of Virginia, not the victim, not the cop, not anyone personally, and his job is to do right by his client. If he decides that means getting an indictment and then nolle pros'ing the case, doing a plea deal, or throwing the cop under the bus (to use the technical term), or even not pursuing a prosecution at all, that's what he's going to do, if it's in the best interests of the Commonwealth.
Because the essence of a "crime" is the offense against the dignity of the Sovereign, the "victim" of every crime is the Commonwealth, not some person who happens to get hurt by the commission of the crime. That person, if he live, is merely a witness as far as criminal procedure goes. As P.N. points out, the next of kin will be best served by conducting their own prosecution in civil court.