There’s a tremendous amount to chew on in this investigation from Andrew Ross Sorkin:

A New York Times examination of mass shootings since the Virginia Tech attack in 2007 reveals how credit cards have become a crucial part of the planning of these massacres. There have been 13 shootings that killed 10 or more people in the last decade, and in at least eight of them, the killers financed their attacks using credit cards. Some used credit to acquire firearms they could not otherwise have afforded.