Actually, making it an adult, say a Wall Street banker, instead of a "gangbanger" only makes me more likely to say we need to devote more resources to the child's murder.
Adults get murdered for all sorts of reasons, and the majority of those murders are actual family murders, and most of the rest are personal grudges. A few are random violence, things like drug deals and robberies gone wrong. From the statistics and gut instinct, whoever killed Mr. Wall Street probably did so either because they personally hated him, or because they wanted to rob him. In the first case, they probably won't kill anyone else, and in the second case, a robbery gone bad, they've probably gone to ground.
In the case of a child murder, the motives are murkier. It could be internal family violence (at which point we have a limited number of suspects to look at). Unfortunately, it could also be one of those rare killers who get off by killing children. Those people are rare, but they tend to keep killing. And they kill more children. If its a family murder, we should be able to figure that out pretty quickly and move on to our banker . . . if its a habitual childkiller they need to be stopped.
Back to the gangster example, and why I would dedicate more resources to the gangster than the banker . . . because the person who killed the gangster is likely another gangster, and this may be the start of a feud that could kill more people.
You all are missing my point. I'm not devaluing the gangster . . . I want to pick the target that is most likely to kill again, and neutralize them. Yes, it factors into the equation whether or not the next victim is likely to be a little kid, or whether it is likely to be an adult who may have some part in their fate (or at least some ability to control it), but my real concern is stopping a possible serial killer (since most people do not have normal motives for killiing children, no matter how bratty they are) before they can kill again. If its an internal family murder, and there are other children in the family, then they may be in danger.
Its not about valuing lives, its about two things . . . stopping the greater threat, and to a lesser extent, protecting the weaker possible victim.
Yeah, I'll admit, assuming the "gangster" really is a "gangster" and not some guy like Romy's friends, I only have so much sympathy for them. (And no, I don't assume "brown and poor" means gang violence . . . just as often its someone who is merely a victim who was in the wrong place) But they (if a criminal) still have a family, and the killer is still a murderer, and they may well have had some decency left . . . and if they are dead we will never find that out.
However, assuming we have the extremely limited facts we have here, I would go after the murderer I thought most likely to kill again, and most likely to target the most helpless victims.