For those contemplating the likely gender of the perp, here are some stats to chew on. In a comprehensive study of homicides committed in the U.S. Over more than a decade, the study revealed the following:
Only 14.7% of the homicides were committed by women, despite females comprising more than half the U.S. population.
In 80% of homicides committed by
men, they killed someone they weren't close to - a casual acquaintance, stranger, or someone of indeterminate relationship.
In 60% of homicides committed by
women, they killed someone they were close to - a spouse, intimate acquaintance, or family member.
http://www.ncbi.nlm.nih.gov/m/pubmed/1635092/
I found a more recent source that claims the number of women who commit murder is not 14.7% as noted in the above study, but is actually 11%.
http://www.bustle.com/articles/1273...yre-predictably-less-common-than-male-killers
What I gather from these stats and articles is that
female murderers are rare (there were only 830 total in the U.S. In 2012). When women do kill, they don't kill strangers or casual acquaintances.
If the total percentage of murders done by women is only 11%, imagine how much lower it goes down when you break it down to murders done by women against women? I wasn't able to find a specific stat on female-on-female murders. If the incidence of females killing females is equal to the incidence of females killing males, then cut that 11% in half. I actually think it might be lower.
So as I see it, the chances that MB was murdered by a female are between 5 and 10 percent.