What you do is need to search with more specifics. When a 69-70 year old woman goes missing/is murdered, what are the stats?
I bet the perp is far more likely to be older than the general stats say. They are, at least, in California.
Arizona is interesting, then, because women are more likely to be murdered by people they know, in other places.
The Scope of the Problem: Intimate Partner Homicide Statistics
While intimate partner homicides are only 1/5th of the total, it is still the main cause. The Arizona stats don't break down:
Other domestic violence (cf the minor league baseball player's BiL slaughtering his whole family this week) including parent child and sibling
Work acquaintances
Friends
Negligent homicide (drunk driving and other)
Provision of drugs (felony drug sales/provision resulting in death - pretty big, too)
Professional misadventure (real estate client, medical relationship)
Anyway, of all the reasons women are killed, homicide by a domestic partner still leads the pack in the rest of the United States (and if Arizona statistics are viewed through the lens of the FBI or the CDC, I think it's true there too).
Also, there are a significant number of unsolved homicides. Very very significant number.