Turns out he was ex-cop.As soon as I read that I though "Police", maybe intelligence. I read another theory he might be in the forces which also makes sense - he tracks his past victims down (part of the fun, sort of like a normal person's crossword or Sudoku) and then taunts them.
Only just finished watching "I'll Be Gone in the Dark" yesterday and fascinating to discover and find out stuff here typed from 8 years ago and he only got caught in recent years.
Somebody in this thread said he seem to stop before DNA testing to help crimes became a thing. So I assume that was one reason he seemed to stop after 1986. Doco never mentioned that or how some guy at town hall meeting was followed home by him and he eventually raped that man's wife. Creepy, this freak actually went to town hall when they all having a meeting how to protect themselves from him.
Cannot imagine being the family to find out your Dad or uncle did these murders and rapes years ago and you had no idea of what this family member was capable of.