Chris Carter said this quote

To start with, the overwhelming majority of serial killers are male,’ Hunter explained. ‘Female serial killers have a tendency to kill for monetary profit. While that can also be true their male counterparts, it’s very unlikely. Sexual reasons top the list for male serial killers. Case studies have also shown that female killers generally kill people close to them, such as husbands, family members, or people dependent on them. Males kill strangers more often. Female serial killers also tend to kill more quietly, with poison or other less violent methods, like suffocation. Male serial killers, on the other hand, show a greater tendency to include torture or mutilation as part of the process of killing. When women are implicated in sadistic homicides, they’ve usually acted in partnership with a man.