Here is a link to a long article that reveals the modus operandi of a serial killer who preyed on marines. There is much truth in what we tell children : "Stranger! Stranger! Danger! Danger!" Unfortunately, there are many adults whose self esteem is so low that they make bad decisions and subsequently find themselves in situations that resemble quicksand. There are predators out there and you need to be aware of this fact.
I met a Convicted Serial Killer