César San Juan
The news of the alleged assassination attempt on the producer and former member of the humorous group "La Trinca" Josep María Mainat by his wife has brought to the present time a casuistry with a lot of literature and little criminological investigation, the murders committed by women.
What is known, because the data say so, is that they are much less than those perpetrated by men, as we will see, and the motivations they are frequently different.
Since Gesche Gottfried was sentenced to death in 1831 for poisoning 15 people with arsenic, all close to her social circle, it would be said that this chemical element has had a certain popularity in later serial killers.
Nannie Doss seduced by the profit motive, poisoned her four husbands with arsenic. As well as Judy Buenoano who with the same motive and with the same substance, ended the lives of her husband, a boyfriend and her 19-year-old son.
In addition to the cases cited, we can remember Kristen Gilbert nurse convicted of killing four patients by injecting them with epinephrine . Or Dorothea Puente who poisoned her older tenants in order to collect their pensions.
There are notable exceptions to these patterns, such as Aileen Wuornos who He shot six men in cold blood. Or Rosemary West and Karla Homolka who, with the collusion of their respective husbands, brutally raped and murdered several adolescent girls.
As we can see, serial killers exist, but their motivations differ significantly from those of their male counterparts, for whom sex and sadism play a greater role.
Assassins are more pragmatic
They tend to take a more pragmatic approach in their crimes, as they are more likely than men to kill for profit or revenge. Likewise, unlike male serial killers, who tend to attack unknown victims, women tend to kill people within their family and social circle .
And finally, continuing with the description of a typically female pattern, we can also point to the tendency of serial killers to poison.
Education and the sociocultural context
Be that as it may, it seems that referring to the violent behavior of women implies putting the focus of attention on an extraordinary phenomenon, since, indeed, if we look at the report on homicides in Spain we can see that only 11% have been perpetrated by women.
The gender ratio that Overwhelmingly pointing to being “male” as the main risk factor for violent behavior has led to the fact that today we know so little about the etiology of aggressive behavior in women.  This knowledge deficit is due to the fact that, in general, an attempt has been made to explain female crime from the perspective of existing theories in relation to crime in general, which could be irrelevant considering the existing gender differences in what concerns, at least, the management of emotions and conflicts, or the differences in family upbringing with girls and boys.
For example, it seems indisputable that more control is exercised in many aspects of life of girls, in particular, in how they spend their free time and the kinds of risks they are allowed to take.
Thus, it is clear that to understand the etiology of violent behavior in women we need different levels of analysis and focus on they, not in men.
Regarding the causes…
In this sense, the review carried out by De nson, O'Dean, Blake & Beames (2018) in which it is evidenced that the magnitude of what we ignore is much higher than what we truly know.
In spite of all that is popularly given for granted and we assume without any margin of reply, even from the criminological sciences, these authors confirm that the neural mechanisms underlying aggression remain poorly understood in women.
Given that in most studies they were not explored gender differences, it is impossible to reach firm conclusions at this time.
The same problem is shared by the ERP studies (event-related potential) measured with electroencephalography and the investigations that analyze the role of certain hormones (testosterone, cortisol, estradiol, progesterone, and oxytocin).
Indeed, the hormonal mechanisms underlying aggression in women are not conclusive and further study is required. ios on the specific social conditions in which some hormones increase or inhibit their aggressive behavior.
… and the consequences
Some authors argue that women have the same probability than men commit CPV (intimate partner violence) although, obviously, men commit a greater number of serious assaults.
In the case of sexual assaults, although they are perpetrated mainly by men, Denson and his collaborators find that a small proportion of these crimes are perpetrated by women, and it is a casuistry about which we know nothing.
It is essential that future research confirm or discard what may be simplistic assumptions about these phenomena and consider the role of women in aggressive relationships.
And what about filicide. Despite the high prevalence of murders of minors at the hands of their parents, there are also women who kill their children. However, because they are such heinous acts that they escape our understanding, there is a tendency to think that they are intrinsically "murderers" and they are intrinsically "sick", so it is more likely to find filicidal fathers in prison and mothers Filicides in the psychiatric .
If we continue to give up exploring our own nature due to ideological inertia or statistical irrelevance, we will be a little further from understanding the etiology of the violent response in women and designing effective prevention strategies based on in the evidence.
About the author: César San Juan is professor of criminal psychology in the Department of Social Psychology of the University of the Basque Country / Euskal Herriko Unibertsitatea