Take the time to get to know them in person, before subjecting yourself to the risk of having met a rapist, or God forbid a serial killer.
It only stands to reason a rapist or serial killer likely has a high degree of charisma and ability to charm one into letting their guard down.
Obviously the chances are slim to none in actually being in the presence and company of a serial killer, but as you’re running the risk of jeopardizing your personal safety and possibly your life, it’s not that great an inconvenience to be cautious.
Can you say “stun gun” or real gun?