I think that the gun made this more likely.
I'd probably disagree with that in this instance, in terms of likelihood
It’s harder to kill with a knife/hammer, and it’s more dangerous to the killer.
Generally, I would absolutely agree with you, which is why the whole "don't ban guns because someone could use a knife instead" argument is fundamentally flawed - however, in this instance, a grown man in the same house as a woman and a young child with them likely to be completely unaware they were about to be attacked - I'd say due to the element of surprise and within a confined environment, 99% of the time, he could have got a kitchen knife and killed her and his daughter whilst she was asleep upstairs. In fact, it would have been easier for him to get a knife and do it without alarming them than it would have been him cracking open the shotgun cabinet and start loading the gun!
Therefore I think having a gun makes it more likely the attack will be fatal.
Again, strictly within this scenario, I think it's debatable. What you'd gain in ultimate devastation with a shotgun, you'd lose in terms of the other party being able to grab it, just plain missing and the other person running for their life, the gun misfiring etc etc
You disagree and seem to think this guy would have killed with any weapon. I don’t think that’s necessarily true. Plus, if they did use a different weapon the likelihood of the victim getting away alive is higher.
In this instance, I'd have to say that I think Kenai is right. If you've got yourself into the mindset where you're going to do something so horrific as to what he did and you didn't have a gun, you'd use a knife. The reason I think it'd go this way is that numerous people who don't have a shotgun and get into this mindset simply use a knife instead and the key issue here is that the victims are all unsuspecting.
There’s not really anyway to get past this as the killer killed the selves so we won’t know why the gun was used over some poison as you suggest.
Poison or something is way different.