Las Vegas shooter Stephen Paddock bought 33 guns within the last year, but that didn't raise any red flags. Some recent mass shooters in the U.S. have amassed arsenals by exploiting limited weapons laws. Others have taken advantage of blind spots in background checks and obtained guns while undergoing mental health treatment. Others got their hands on weapons that were initially purchased legally. As in the Navy Yard case, Holmes' treatment alone did not prevent him from buying guns.

Source: ABC News October 04, 2017 21:16 UTC