Episodes of mass-murder are written up in books and so men who generate these acts "make history." The actions and writing about the actions are not independent variables.

Mass-murderers and historians collaborate.

Mass-murderers are acutely aware of their primary audience: historians, who keep the "record books." They are like those who shouted out to Rudolph the Red-Nosed Reindeer after he performed his heroic acts: "You'll go down in history." 

Koenigsberg