Cop kills wife and 5 year old son then himself, all were shot in the head !

I don't really think the numbers  back that up, especially in light of the OP, things like school shootings, parking of shootings where congress women get a bullet in the head, etc. The city I live in has been told by one of our national news magazines as having the worst neighborhood in Canada. We have a very high percentage of native youth who don't really have much of a hjop of succeeding at anything, kids who are victims of multi generational poor parentung and multi generational welfare.

We have gang wars here between native gangs, white gangs and Asian gangs.

But for murders, not so many, maybe a dozen per year on average (and we have the highest murder rate in Canada).

I would ask that when you are comparing numbers between countries, that you ensure that everything is being taken into account.

For example, the British tend to report any complaint as part of their statistics. Does the USA do that, or does it just count convictions?

You have to be prepared, sometimes, to do some pretty in depth analysis to get to the real numbers because every country has a different reporting scale.