Define Story Back Meaning

I've heard this used on CNN a couple of times. "Back story" is used when talking about a breaking news story, when the rest of the story isn't clear. "What is the back-story on the train crash?" Meaning how many were on the train. When did it leave, and how fast was it going?

“....and then I wanted to plant tulips but I just don’t think our soil is right for it...”
“Sir! I just need to know, soup or salad!” Said the poor waitress after a 5 minute story from the Back Story Bore on table 8.

“Can I get your name please, ma’am?”
“Well I called because I got this letter and I was going to call yesterday when I got it but then my sister called and then it started to rain so I had to....”
“MA’AM!!! I need your name before I can even help you!” Denise screamed at the back story bore who was eating into her lunch hour.

Ya he used a story back