Ideally a lawsuit? The only sane outcome of this in a civilized society is that the perpetrator stands trial for murder.
If that does not happen the already slim distinction between US law enforcement and a paramilitary execution squad loyal to the president will have dissappeared entirely.
Even if there is a perceived slim chance of success I still think charges should be brought forward. At the very least it might make some of these psychopaths hesitate to do the same. Maybe. And while they are at it maybe an investigation that produces names on who ordered these guys to act so brazen.
If you cant nail the guy who did this go after those who are above in rank. Maybe there's a "paper trail" on giving orders to do such thing?
People have to fight back or this lady definitely wont be the last.