You'd have to look into state laws and previous cases where a gun purchase being tied to some murder got someone convicted. I'm not going to hunt it down to prove it to you but you're free to spend your time doing so.
I mean a source for most states saying there is a duty to report a stolen firearm and that there is halting for failure to report it. I was able to find a list of states where it is indeed illegal but that is only 11.
What I'm saying is "No I do not have an article that lays out state laws succinctly, you'd have to search the actual .gov pages for the laws themselves, and as I am not your paralegal and not getting paid for my work I am declining to do it."
Or you could just do some thinkin' and realize "Yeah if a gun that I did a NICs check on that got stolen shows up in a murder and I don't have an alibi, I might be a suspect in said murder" isn't actually that wild of a situation. If you can't see how it could be likely though, like I said, you're free to search yourself.
The source is there in the statutes laid out by the state, I'm unwilling to aggregate it for you, as I have a whole other job I'm doing that actually pays me. You are free to look em up yourself.
So basically you made a claim that you cannot back up. It's not my job to research claims you make.
Your scenario makes me think you watch waaaay too many cop shows. The probability that a gun is used in a murder is pretty low. The probability that police look into where the gun actually came from is extremely low. Otherwise straw purchasing would not be a thing which it very much is.
Probability that a murder is done by a gun != the probability that a specific gun is used to murder someone. I hope you are not naive enough to think that every illegal gun is used to murder people.
Oh definitely not, actually if you look at the math of how many guns there are in the country VS how many are used in murders it's basically just a rounding error. That's actually why it makes me laugh when people demonize all gun owners like they're all just one day away from killing. Statistically that isn't the case. Of course nobody made that claim, so "cool" I guess.
Still though, if they find a gun at the scene with a serial number and NICs says that Steve's Pawn sold it and Steve's Pawn's paperwork says it was sold to Joe Smith, Joe better have a good alibi in most states or else he may find himself in court defending his innocence because "It was stolen and I never reported it" is a very shaky pretense for a defense, the DA could believe you, but it's unlikely.
Or not, whatever, believe what you wish idgaf. I wouldn't take "oh I live in X state so I don't legally have to report stolen guns" to be a good idea myself but you're free to make your own decisions regarding your stolen guns I guess. Personally I'd report it anyway to avoid future questions and hopefully recover my stolen property, but that's just me, obviously you disagree since you're so dead set against me on that.
Oh, unless of course you mean in cases where the gun isn't found, in which case all this is moot because without the gun there's no serial number to tie it to anyone anyway, it may as well be unreported. Of course they have to have the gun. Not sure why you are going on a tangent about "not all illegal guns are used to murder people," because typically ones found at murder scenes were, and if it is tied to a NICs check you did and you haven't reported it stolen, know what? Just come on back here and let us know how it went for ya.