The Live-in Lover Problem

I have blogged before (here for example) about the tragic frequency of violence perpetrated by men living with women who have children from previous relationships.

Another dreadful example came to court just the other day: a man killed his girlfriend of two year's standing, leaving a three year old boy without a mother.

The questions I asked before seem just as pertinent now as then:

Is there a disproportionate frequency of abuse and murder of women and children by men living with women who have children by previous relationships?

If so, is there a causative link between such patterns of relationship and abuse, or is it merely a co-factor of other determinants (eg chaotic life style, educational levels, deprivation, poverty)?

But I have yet to see any research, or even commentary, on this.  It simply doesn't fit with the desired narrative of our modern society.