Lexicus
Deity
I guess the density rather than per head rate would matter if most homicide is simply an accident of location. Which doesn't seem like that'd be it. Unless, of course, the people are immobile. Like in wheelchairs, or women in the early 19th century. Or if suicide is spontaneous instead of culmination of factors over time.
I think the density of people clearly matters with regard to opportunity to commit homicides. I don't think spatial distribution of people is relevant to suicide in the same way.