Oh I remember this story. It was so strange!! I think maybe even Dateline did a story on this way back.Yes! Documentaries! Serial killers! I think I've seen them all!
And yes the other person does become quite annoyed!
There is a documentary on YouTube called There's Something Wrong with Aunt Diane, read about it before you watch it though. Not a serial killer but a case I had been following-though many will find it very disturbing.