1). Yes.  That a good benefit of having a background check.  But that doesn't mitigate the benefit of having a registration system.

2). Yes, it's a TV show and no, DNA does not just leap off of you and cling to everything and remain usable for years.  I just gave you the means of DNA depositing: blood, semen, saliva, hair follicles.  And they have to be in sufficient quantity and quality to be usable.  And, even if you did get a sample with usable markers, their DNA would need to already be documented in CODIS to get a match.

3). Every gun already has a serial number on them. Yes, you can file off the serial number on some guns (this isn't done very often) but that in itself is illegal already. It's a felony to remove it, sell one that had the serial number removed (even if you didn't remove it yourself), buy one without one, posses one without it, etc...

4). I still don't get how that prevents a future crime.  Your logic suggests that anybody that passes a background check will never commit a gun related crime.

5). I just told you that article discusses ballistics.  It only references DNA to draw an analogy with how ballistics examinations can be used to link a gun to a given crime.

No. There are people that commit crimes for the first time but the odds of a criminal committing multiple crimes are really high because of how we treat them.

The study links methods they use for DNA testing and it works for that so it works to identify the guns.

What experience?

>Well you didn't use that wonderful word called "other(s)" before, which you did to explain yourself this time around, so that would change how it reads. I'm still not sure why pointing out political motivation is odd, since it seems it's being pointed out for other reasons in other situations.

My original sentence was "they're concerned about A or they're concerned about B".  Putting "others" doesn't make sense in that sentence.  "others" would make sense if the sentence was "they're concerned about A and others are concerned about B."  

>So I must then ask if any liberals feel this way?

Are there some?  Absolutely.  But I'm actually talking about something slightly different.  Some fundamentalist Christians view women as basically birthing canals that aren't allowed to get jobs.  That viewpoint, you can certainly find some liberals who feel that way, but it's less common.

>so why should a crazy person be believed when they write an explanation as to why they did something?

The person drove 9 hours to a major town near the border, and published a manifesto about said town minutes before shooting.  There is a clear political implication there.  

Just because someone is crazy doesn't mean they don't have reasons that make sense to them.  

I'm not saying the second shooting definitely isn't left wing politically motivated, I am saying there is no evidence so far for that to be the case. 

1). We already have states with background checks.  Does it prevent all gun related crime?  As for infringing on rights....how about the right to not get shot up?

2). I don't care how often you use the gun, where the hell is the DNA going to come from?  In what form? How is it going to remain collectable and viable for lab use? And yes, Law and Order makes it look easier than it is too. Hell, most police departments don't even have a DNA lab.  Even a city like NYC only tests a few of the guns they recover for DNA.

3). Precisely my point.  Serial numbers are not often removed.  Meaning they are a valid way of tracing gun to owner.

4). Really? You are aware that most of these mass shooters bought their own guns AND passed a background check, right?

5). What do you mean the methods are similar?  Do you know what ballistics and DNA are and how they are analyzed?

1). Point 4 of your post just showed that states still have mass shootings even with background checks.  That means legally purchased by an owner with a background check still committed a mass shooting. That means that even with background checks, you still get legally purchased firearms being used by their owner to commit crimes.  Hence the validity of registration in investigating said crimes.

2). Cough - saliva.  Saliva evaporates pretty quickly because it's 99% water.  Even if some did remain, only 60% of the epithelial cells from the oral mucosa even in a test swab are contain viable DNA.  And even then you have be sure it's human DNA because saliva is heavily comprised of bacteria and your samples will have 100x more bacterial DNA than human DNA. And we have haven't even begun to talk about contamination and atmospheric degradation. 

Hair - needs to have the bulb attached for DNA examination.  Hair you shave, gets tugged, stretched, cut, etc... does not have the bulb attached.

3). You can't 'rip them off'.  They are laser etched into it.  Some can be filed away if there is sufficient room to use a file.  Some can be corroded away with a strong acid.  Either way, let's get back to the part where doing that, owing one a gun without a serial number, selling one, buying one, etc...is already a major felony.  So, they won't be a large group that removes their serial number.

4). Good.  Glad to see that.  Let's get that national background check program going then. 

5). Gather is the same?  DNA is collected via swabs, blood extraction, etc...  Ballistic evidence is bullet/gun collection from victim/scene and test firing a round from that gun for comparison.   The similarities are simply comparing a known against an unknown or a database.  But that's the underlying concept of half of all forensics.  Friction ridges (fingerprints), shoe treads, tire treads, dental records, trace evidence, chemical analysis, fibers, makeup, explosives, tool mark examination, urinalysis, toxicology, paint, glass, and on and on...are all about matching knows to unknowns and/or a database.

That's why I didn't even bother with skin sourced DNA.  Transferability, false-positives, contamination and degradation are just too high to make it viable.  In fact, it's my understanding that it is used more by the defense than prosecution.

1). Point 4 of your post just showed that states still have mass shootings even with background checks.  That means legally purchased by an owner with a background check still committed a mass shooting. That means that even with background checks, you still get legally purchased firearms being used by their owner to commit crimes.  Hence the validity of registration in investigating said crimes.

2). Cough - saliva.  Saliva evaporates pretty quickly because it's 99% water.  Even if some did remain, only 60% of the epithelial cells from the oral mucosa even in a test swab are contain viable DNA.  And even then you have be sure it's human DNA because saliva is heavily comprised of bacteria and your samples will have 100x more bacterial DNA than human DNA. And we have haven't even begun to talk about contamination and atmospheric degradation. 

Hair - needs to have the bulb attached for DNA examination.  Hair you shave, gets tugged, stretched, cut, etc... does not have the bulb attached.

3). You can't 'rip them off'.  They are laser etched into it.  Some can be filed away if there is sufficient room to use a file.  Some can be corroded away with a strong acid.  Either way, let's get back to the part where doing that, owing one a gun without a serial number, selling one, buying one, etc...is already a major felony.  So, they won't be a large group that removes their serial number.

4). Good.  Glad to see that.  Let's get that national background check program going then. 

5). Gather is the same?  DNA is collected via swabs, blood extraction, etc...  Ballistic evidence is bullet/gun collection from victim/scene and test firing a round from that gun for comparison.   The similarities are simply comparing a known against an unknown or a database.  But that's the underlying concept of half of all forensics.  Friction ridges (fingerprints), shoe treads, tire treads, dental records, trace evidence, chemical analysis, fibers, makeup, explosives, tool mark examination, urinalysis, toxicology, paint, glass, and on and on...are all about matching knows to unknowns and/or a database.

Anyway there's really not much I can add from here. I don't think registration is good because I don't like the feds keeping track of people's purchases and there are other ways to solve crimes. You don't care if they track what you buy and don't think the methods we have now are sufficient enough. There's really no middle ground here and I doubt were gonna change each others mind.