No matter the circumstances, if you have shot someone, that firearm WILL be seized as evidence at least until the investigation is complete. If the investigating officer doesn't seize the firearm, he is negligent in his responsibility. Evidence not seized initially is either lost all together or compromised at best..../
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Someone posted the comment above, and it's very black and white. Arguably a little too black and white. It's the kind of too black and white view of the world that also leads to officers rolling up on a scene and then reacting or overreacting before they take the time to figure out what's happening and what action is needed.
It's emblematic of a risk averse approach to law enforcement focused on controlling the scene as a justification for whatever comes next. It's an "arrest them all and let the courts sort them out" approach to law enforcement, rather than a focus on using appropriate officer discretion and maintaining order.
It's the kind of black and white interpretation that when taken too far results in other people overreacting and screaming to "defund" the police, when what's needed is better training on appropriate use of officer discretion.
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Let's look at the OP's question from a castle doctrine perspective in NC - and when seizing a weapon for evidentiary purposes makes sense and when it doesn't - because it sometimes doesn't make sense.
In NC, the castle doctrine extends to your vehicle. If you pull up to a stop light, someone tries to pull you out of your car, you are justified in using lethal force to prevent that. It's not about preventing your car from being stolen, it's about the threat to your life when you are being pulled from your car. You have a right to assume they intend to kill you or cause serious bodily injury to you, or to family members or others in your car.
Now...there can always be more to the story and the rest of the story might have an impact on the legality of the shoot. One of the things to consider is that in NC you forfeit the right to self defense if you were initially the aggressor. In the above case, if the you, as the person being pulled from the car had cut off the guy pulling you from the car, got in a verbal argument with him, flipped him off and then threatened him before you proceeded to the next stop light, it's now not nearly as clean. In that case you should expect to be arrested and held until the District Attorney's office can decide whether you should be charged. That decision will hinge on whether or not it can be determined if you had initially been the aggressor and or whether or not your actions after that event were sufficient to constitute a "retreat" that restored your right to self defense. Maybe. Maybe not, it'll all come down to subtle details and an arrest is warranted.
Either way, if you did something like, you are in fact an idiot. If you really plan on carrying a handgun for self defense and want to be able to use self defense as a justification, you need to be very polite and learn how to turn the other cheek, right up to the point that a credible threat of death or serious bodily injury actually occurs, with no aggravating or escalating behavior on your part. An armed society is a polite society - not just because people carry guns, but because they want to preserve the right to use them when necessary.
In that case, since you are being arrested (in large par as a result of being a hot headed idiot) taking custody of your firearm naturally follows. Whether it is evidence or not, the officer(s) at the scene are not going to just leave it there at the scene.
On the other hand if there is no evidence of a precipitating event or you contributing to the events leading up to the shoot, and there are witnesses who saw the guy you shot hanging out on the corner, approaching your car and pulling you out without any provocation, it's a lot clearer what happened and that your use of lethal force was justified.
If the guy you shot happens to have a prior record or outstanding warrants for car theft, assault, etc, it's even clearer.
In the extreme, if you also had your wife and/or children in the car, you also had reason to fear what the guy you shot planned to do with them. If the guy you shot also has a prior record or outstanding warrants for assault, rape, etc, and there are also witnesses who support your statement of what happened, then it's crystal clear.
In this latter case, you should not be arrested and there is also no need to take your handgun into evidence. An officer is certainly justified in securing the handgun at the scene until it becomes apparent what happened. It also makes sense to verify your story in terms of counting and accounting for the spent brass at the scene and cross checking that - and you account of events - by verifying the number of rounds left in the magazine. It also makes sense to document the serial number on the handgun and back it up with a picture of the handgun, magazine and remaining rounds. Then give the gun and his concealed carry permit back with the guy when you send him on his way.
In that case there isn't any real value in confiscating the firearm. There is no evidence you committed a crime (Although that would be different in a state like VA where a self defense shoot requires a second degree murder charge and an affirmative defense).
Worst case, the officer has evidence in the form of one or more bullets in the guy who was shot that can be matched to the gun you documented at the scene at a later date in the unlikely and unforeseen circumstance that evidence arises that it might not have been as clean as you and everyone else involved thought.
That's particularly true with a handgun like a CZ where the serial number is on the frame, the slide and the barrel, precluding the ability to swap slides and barrels to confound future ballistic testing. That effort would in and of itself be incriminating, as would disposing of the gun.
In short, there's not much if any upside to seizing a firearm in a shoot that is clearly a good shoot with ample evidence at the scene to confirm it was a justified use of self defense. Seizing a firearm in that situation is just risk averse butt covering, and once an officer goes down that road, other risk averse people will ensure it takes months or years to return it to the owner.
If that evidence of a clearly justified use of self defense is not present and the status of the shoot is not obvious then the firearm should be taken into evidence, but that will be based on the ambiguous nature of the shoot, or perhaps a clear violation of concealed carry privileges of the shooter, where you'd confiscate the concealed carry permit as well, until the issue is sorted out.
