Within 2 days he decided to do this, bought the gun, and killed the people. If he didn't have such easy access to a gun, those people would be alive tonight. if he has to go through training and licensing to get a gun, he probably doesn't even bother. If he had to use some other weapon besides a gun, he probably doesn't even do it, and even if he tried, they have a much better chance at surviving.
Nobody suggests that the murder rate would go to zero, only that it could decline. As could suicide rates and gun related accidental death rates. We don't expect traffic fatalities to get to zero, that doesn't mean we don't continue to make car safer.
I don't have the time today to do this argument justice, so I'll throw up a few links at the end of this blurb and hope people will look into it themselves.
The primary issue I have with this whole debate is people trying to determine the outcome of the future based on specific past events: IE This particular guy went out, bought a gun, and murdered 3 people, therefore had he not had access to a gun, this crime wouldn't have happened. That's absolutely impossible to know, and I'm not saying that to be facetious. There is almost 0 correlation between a country's homicide rate and gun control. I am serious about that, universally homicide rates are barely, if at all, affected by gun laws. In some cases, the rates increase, which makes sense in a low correlation situation. The same holds true for suicide rates, accidental deaths, etc.
Yet there is some correlation about the increase in violent crime overall in a country which has banned guns. There is evidence that certain events, such as random rape, actually increase with gun bans, which logically wouldn't be anticipated.
I don't own a gun, nor do I have any desire to own one. I don't have a strong view on this particular topic, and if guns were outlawed tomorrow I doubt it would impact my life in any truly meaningful way. That said, I also think the argument for that ban is disingenuous. We are creating the illusion that if guns were banned, so much of the crime and violence in this country would be solved. That the very existence of firearms in our country creates the culture we don't understand and detest, and enables mass murders. The problem is, evidence shows these issues exist separately from the weaponry entirely.
I think we spend way too much time and energy debating surface issues because the more difficult tasks of integrating multiple cultures and ideologies in this country is more difficult to solve. If you want to lower violent crime, find a way to identify people with substantial stress or poor mental states early, find a way to provide treatment and relief, or in extreme cases, find a way to get them removed from society until they're capable of being reintegrated safely. Find a way to reduce the effects of unintentional racism, and reduce the sense of experiencing racism for minorities.
Of course, that doesn't happen when neighbors keep their doors locked and don't interact, families cast out the odd balls, and we foster a natural darwinistic aggression in all facets of life.
Following:
Links from unbiased or mostly unbiased sources on the effects of gun bans and the effect on actual homicides and crime (Note: Not gun-related homicide, which would obviously drop as expected from outlawing guns. People just find other, more inventive ways to kill each other)
https://www.justfacts.com/guncontrol.asp (Independent site which provides data without attempting to draw meaningful conclusions)
http://web.archive.org/web/20131125...nts/orgs/jlpp/Vol30_No2_KatesMauseronline.pdf This is a Harvard study specifically on the murder and violent crime correlation as it pertains to gun control. I have skimmed it, but honestly haven't read all of it in its entirety. That said, I'd recommend looking at the tables and granting the researchers some trust in the conclusions he draws at the end of the document.
http://www.washingtonpost.com/news/...-a-central-thesis-of-the-gun-rights-movement/ A Washington Post article which discusses a bit of research that concluded more guns means less crime, and revisited 10 years later with updated data determined more guns means more crime. The latter here isn't the full conclusion drawn by researchers however, they simply determine that the correlation between guns and crime is low, if not 0, and the data trying to relate the two will likely vary based on when samples are taken.
I could go on, and I'd recommend looking into the impact on homicide and violent crime overall in countries which have imposed gun bans such as England, for evidence of a lack of expected correlation.